Changes to Policy set API for PPRV

[mrinalirao]

Description

Add support to the go-tfe client for creating sentinel policy sets that will be run within the agent against a pinned policy tool version. FYI: Pinned Policy Runtime version is now GA.

It also removes beta tags from old OPA tests as OPA is now in GA

Api's updated:

Policy set creation (Adds agent-enabled + policy-tool-version attribute)

Testing plan
Integration tests added

External links
JIRA

Output from tests
Needs the following env vars:
TFE_ADDRESS
TFE_TOKEN
Set ENABLE_BETA=1

envchain staging go test -run TestPolicySetsCreate -v ./... -tags=integration
=== RUN TestPolicySetsCreate
=== RUN TestPolicySetsCreate/with_valid_attributes
=== RUN TestPolicySetsCreate/with_kind_missing
=== RUN TestPolicySetsCreate/with_agent_enabled_missing
--- PASS: TestPolicySetsCreate (1.45s)
--- PASS: TestPolicySetsCreate/with_valid_attributes (0.25s)
--- PASS: TestPolicySetsCreate/with_kind_missing (0.32s)
--- PASS: TestPolicySetsCreate/with_agent_enabled_missing (0.23s)
PASS
ok github.com/hashicorp/go-tfe 2.317s
? github.com/hashicorp/go-tfe/examples/configuration_versions [no test files]
? github.com/hashicorp/go-tfe/examples/organizations [no test files]
? github.com/hashicorp/go-tfe/examples/registry_modules [no test files]
? github.com/hashicorp/go-tfe/examples/state_versions [no test files]
? github.com/hashicorp/go-tfe/examples/users [no test files]
? github.com/hashicorp/go-tfe/examples/workspaces [no test files]
? github.com/hashicorp/go-tfe/mocks [no test files]

envchain staging go test -run TestPolicySetsUpdate -v ./... -tags=integration
=== RUN TestPolicySetsUpdate
=== RUN TestPolicySetsUpdate/with_valid_attributes
--- PASS: TestPolicySetsUpdate (1.61s)
--- PASS: TestPolicySetsUpdate/with_valid_attributes (0.30s)
PASS
ok github.com/hashicorp/go-tfe 2.301s
? github.com/hashicorp/go-tfe/examples/configuration_versions [no test files]
? github.com/hashicorp/go-tfe/examples/organizations [no test files]
? github.com/hashicorp/go-tfe/examples/registry_modules [no test files]
? github.com/hashicorp/go-tfe/examples/state_versions [no test files]
? github.com/hashicorp/go-tfe/examples/users [no test files]
? github.com/hashicorp/go-tfe/examples/workspaces [no test files]
? github.com/hashicorp/go-tfe/mocks [no test files]

envchain staging go test -run TestPolicySetsList -v ./... -tags=integration
=== RUN TestPolicySetsList
=== RUN TestPolicySetsList/without_list_options
--- PASS: TestPolicySetsList (2.90s)
--- PASS: TestPolicySetsList/without_list_options (0.51s)
PASS
ok github.com/hashicorp/go-tfe 3.726s
? github.com/hashicorp/go-tfe/examples/configuration_versions [no test files]
? github.com/hashicorp/go-tfe/examples/organizations [no test files]
? github.com/hashicorp/go-tfe/examples/registry_modules [no test files]
? github.com/hashicorp/go-tfe/examples/state_versions [no test files]
? github.com/hashicorp/go-tfe/examples/users [no test files]
? github.com/hashicorp/go-tfe/examples/workspaces [no test files]
? github.com/hashicorp/go-tfe/mocks [no test files]

[nfagerlund]

I haven't fully reviewed the code yet, but there was one glaring problem (in multiple places) that jumped out at me, and I wanted to send it back to you as soon as I could. I'll take another look once you've got that sorted out!

[nfagerlund]

Ok, this is mostly looking good, other than one missing omitempty. My only other real concern at this point is making sure the doc comments are easy to understand. Comments inline.

[github-actions]

Reminder to the contributor that merged this PR: if your changes have added important functionality or fixed a relevant bug, open a follow-up PR to update CHANGELOG.md with a note on your changes.