Remove trailing commas in CodeGen

[trivikr]

The repo aws/aws-sdk-js-v3 uses prettier for formatting which doesn't add trailing commas by default. And we plan to continue using default options of prettier
Docs: https://prettier.io/docs/en/options.html#trailing-commas

We're running prettier on precommit hook to overwrite code generated by CodeGen aws/aws-sdk-js-v3#631
And noticed that trailing commas are added by smithy-typescript-codegen in aws/aws-sdk-js-v3@5f9fbfc

It's optional for smithy-typescript to remove addition of trailing commas.
It won't affect aws/aws-sdk-js-v3 as prettier overwrites the code on precommit hook.

[trivikr]

prettier throws following error in zsh while doing CodeGen for multiple packages:

zsh: argument list too long: prettier

I faced this error while generating rest-json clients aws/aws-sdk-js-v3#643, fixed it temporarily by switching to bash

[trivikr]

lint-staged showed the following warning while committing update to aws.json-1.1 clients:

⚠  lint-staged generated an argument string of 237405 characters, and commands might not run correctly on your platform.
It is recommended to use functions as linters and split your command based on the number of staged files. For more info, please visit:
https://github.com/okonet/lint-staged#using-js-functions-to-customize-linter-commands

Screenshot:

The number of files which need to be prettified at lint-staged can be reduced if trailing comma is removed in codegen

[trivikr]

fixed it temporarily by switching to bash

The fix is not working anymore in bash, and git commit fails with following error

spawn E2BIG

I faced this issue while updating clients with fix from aws/aws-sdk-js-v3#696

The prettier command also fails in bash:

$ prettier --write client-*/**/*.ts
bash: /Users/trivikr/.nvm/versions/node/v12.14.0/bin/prettier: Argument list too long

[trivikr]

Temporarily fixed the issue by running prettier on each file instead:

$ git diff --name-only --cached | xargs -I '{}' prettier --write '{}'

[trivikr]

Running prettier on each staged file takes lot of time

A faster fix is running prettier per client instead of per file

for f in clients/*
do
  ./node_modules/.bin/prettier --write $f/**/*.{ts,md,json}
done

[trivikr]

temporary commit which added aws.json-1.0 clients without running prettier trivikr/aws-sdk-js-v3@476e88b

It has several changes other than trailing commas, as shown in the screenshot below

As discussed offline:

• CodeGen will only be responsible for generating valid TypeScript code
• Formatting (and in future linting) will be done by JavaScript code in aws-sdk-js-v3

Closing this in favor of aws/aws-sdk-js-v3#698