feat: add replica support

[yoshi-automation]

This PR was generated using Autosynth. 🌈

Log from Synthtool

synthtool > Executing /tmpfs/src/git/autosynth/working_repo/synth.py.
synthtool > Ensuring dependencies.
synthtool > Pulling artman image.
latest: Pulling from googleapis/artman
Digest: sha256:75b38a3b073a7b243545f2332463096624c802bb1e56b8cb6f22ba1ecd325fa9
Status: Image is up to date for googleapis/artman:latest
synthtool > Cloning googleapis.
synthtool > Running generator for google/spanner/artman_spanner.yaml.
synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/js/spanner-v1.
synthtool > Running generator for google/spanner/admin/database/artman_spanner_admin_database.yaml.
synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/js/spanner-admin-database-v1.
synthtool > Running generator for google/spanner/admin/instance/artman_spanner_admin_instance.yaml.
synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/js/spanner-admin-instance-v1.
.eslintignore
.eslintrc.yml
.github/ISSUE_TEMPLATE/bug_report.md
.github/ISSUE_TEMPLATE/feature_request.md
.github/ISSUE_TEMPLATE/support_request.md
.github/PULL_REQUEST_TEMPLATE.md
.github/release-please.yml
.jsdoc.js
.kokoro/common.cfg
.kokoro/continuous/node10/common.cfg
.kokoro/continuous/node10/docs.cfg
.kokoro/continuous/node10/lint.cfg
.kokoro/continuous/node10/samples-test.cfg
.kokoro/continuous/node10/system-test.cfg
.kokoro/continuous/node10/test.cfg
.kokoro/continuous/node12/common.cfg
.kokoro/continuous/node12/test.cfg
.kokoro/continuous/node8/common.cfg
.kokoro/continuous/node8/test.cfg
.kokoro/docs.sh
.kokoro/lint.sh
.kokoro/presubmit/node10/common.cfg
.kokoro/presubmit/node10/docs.cfg
.kokoro/presubmit/node10/lint.cfg
.kokoro/presubmit/node10/samples-test.cfg
.kokoro/presubmit/node10/system-test.cfg
.kokoro/presubmit/node10/test.cfg
.kokoro/presubmit/node12/common.cfg
.kokoro/presubmit/node12/test.cfg
.kokoro/presubmit/node8/common.cfg
.kokoro/presubmit/node8/test.cfg
.kokoro/presubmit/windows/common.cfg
.kokoro/presubmit/windows/test.cfg
.kokoro/publish.sh
.kokoro/release/docs.cfg
.kokoro/release/docs.sh
.kokoro/release/publish.cfg
.kokoro/samples-test.sh
.kokoro/system-test.sh
.kokoro/test.bat
.kokoro/test.sh
.kokoro/trampoline.sh
.nycrc
.prettierignore
.prettierrc
CODE_OF_CONDUCT.md
CONTRIBUTING.md
LICENSE
README.md
codecov.yaml
renovate.json
samples/README.md
synthtool > Replaced "(const SpannerClient = require\\('\\./spanner_client'\\);)" in src/v1/index.js.
synthtool > Replaced '(module\\.exports\\.SpannerClient = SpannerClient;)' in src/v1/index.js.
synthtool > Replaced '../../package.json' in src/v1/database_admin_client.js.
synthtool > Replaced '../../package.json' in src/v1/instance_admin_client.js.
synthtool > Replaced '../../package.json' in src/v1/spanner_client.js.
synthtool > Replaced 'https:\\/\\/cloud\\.google\\.com[\\s\\*]*http:\\/\\/(.*)[\\s\\*]*\\)' in src/v1/doc/google/protobuf/doc_timestamp.js.
synthtool > No replacements made in **/doc/google/protobuf/doc_timestamp.js for pattern toISOString\], maybe replacement is not longer needed?
synthtool > Replaced '`\\[a-z\\]\\(https:\\/\\/cloud\\.google\\.com\\[-a-z0-9\\]\\*\\[a-z0-9\\]\\)\\?`' in src/v1/doc/google/spanner/admin/instance/v1/doc_spanner_instance_admin.js.
synthtool > Replaced '`\\[a-z\\]\\(https:\\/\\/cloud\\.google\\.com\\[-a-z0-9\\]\\*\\[a-z0-9\\]\\)\\?`' in src/v1/doc/google/spanner/v1/doc_spanner.js.
synthtool > Replaced '`\\(\\[a-z\\]\\(https:\\/\\/cloud\\.google\\.com\\[-a-z0-9\\]\\*\\[a-z0-9\\]\\)\\?\\)\\?`' in src/v1/doc/google/spanner/admin/instance/v1/doc_spanner_instance_admin.js.
synthtool > Replaced '`\\(\\[a-z\\]\\(https:\\/\\/cloud\\.google\\.com\\[-a-z0-9\\]\\*\\[a-z0-9\\]\\)\\?\\)\\?`' in src/v1/doc/google/spanner/v1/doc_spanner.js.
npm WARN npm npm does not support Node.js v12.13.0
npm WARN npm You should probably upgrade to a newer version of node as we
npm WARN npm can't make any promises that npm will work with this version.
npm WARN npm Supported releases of Node.js are the latest release of 6, 8, 9, 10, 11.
npm WARN npm You can find the latest version at https://nodejs.org/

> [email protected] install /tmpfs/src/git/autosynth/working_repo/node_modules/grpc
> node-pre-gyp install --fallback-to-build --library=static_library

node-pre-gyp WARN Using needle for node-pre-gyp https download 
[grpc] Success: "/tmpfs/src/git/autosynth/working_repo/node_modules/grpc/src/node/extension_binary/node-v72-linux-x64-glibc/grpc_node.node" is installed via remote

> [email protected] postinstall /tmpfs/src/git/autosynth/working_repo/node_modules/core-js
> node postinstall || echo "ignore"

Thank you for using core-js ( https://github.com/zloirock/core-js ) for polyfilling JavaScript standard library!

The project needs your help! Please consider supporting of core-js on Open Collective or Patreon: 
> https://opencollective.com/core-js 
> https://www.patreon.com/zloirock 

Also, the author of core-js ( https://github.com/zloirock ) is looking for a good job -)


> [email protected] postinstall /tmpfs/src/git/autosynth/working_repo/node_modules/protobufjs
> node scripts/postinstall


> @google-cloud/[email protected] prepare /tmpfs/src/git/autosynth/working_repo
> npm run compile

npm WARN npm npm does not support Node.js v12.13.0
npm WARN npm You should probably upgrade to a newer version of node as we
npm WARN npm can't make any promises that npm will work with this version.
npm WARN npm Supported releases of Node.js are the latest release of 6, 8, 9, 10, 11.
npm WARN npm You can find the latest version at https://nodejs.org/

> @google-cloud/[email protected] compile /tmpfs/src/git/autosynth/working_repo
> tsc -p . && cp -r src/v1 build/src && cp -r protos build && cp -r proto build && cp test/*.js build/test

npm notice created a lockfile as package-lock.json. You should commit this file.
added 793 packages from 1312 contributors and audited 2394 packages in 24.586s
found 0 vulnerabilities

npm WARN npm npm does not support Node.js v12.13.0
npm WARN npm You should probably upgrade to a newer version of node as we
npm WARN npm can't make any promises that npm will work with this version.
npm WARN npm Supported releases of Node.js are the latest release of 6, 8, 9, 10, 11.
npm WARN npm You can find the latest version at https://nodejs.org/

> @google-cloud/[email protected] fix /tmpfs/src/git/autosynth/working_repo
> gts fix && eslint --fix '**/*.js'

installing semver@^5.5.0
installing minimist@^1.2.0
installing espree@^3.5.4
synthtool > Cleaned up 2 temporary directories.
synthtool > Wrote metadata to synth.metadata.

[codecov]

Codecov Report

Merging #726 into master will decrease coverage by 0.01%.
The diff coverage is 75.09%.

@@            Coverage Diff            @@
##           master    #726      +/-   ##
=========================================
- Coverage   96.12%   96.1%   -0.02%     
=========================================
  Files          18      18              
  Lines       15607   15599       -8     
  Branches      532     532              
=========================================
- Hits        15002   14992      -10     
- Misses        600     602       +2     
  Partials        5       5

Impacted Files	Coverage Δ
src/v1/spanner_client.js	76.16% <40.8%> (-0.65%)	⬇️
src/v1/instance_admin_client.js	96.79% <88.42%> (+0.19%)	⬆️
src/v1/database_admin_client.js	96.59% <94.6%> (+0.51%)	⬆️

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