Adds Agent Pool to OAuth Client API

[roleesinhaHC]

Description

Currently, Private VCS support is enabled in TFC behind feature flag. This PR include changes to add API support for Private VCS by enabling creation of OAuth Client when AgentPoolID is set (as an optional param).

Testing plan

1. Enable Private VCS for in a test org.
2. Create an Agent Pool in the org.
3. Launch an tfc-agent running locally.
4. Execute the oauth_client creation API and pass the agent_pool_id as a param.

Output from tests

Including output from tests may require access to a TFE instance. Ignore this section if you have no environment to test against.

go-tfe % TFE_TOKEN= TFE_ADDRESS= OAUTH_CLIENT_GITHUB_TOKEN= go test -run TestOAuthClientsCreate_agentPool -v ./...
?       github.com/hashicorp/go-tfe/examples/backing_data       [no test files]
?       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/run_errors [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]
=== RUN   TestOAuthClientsCreate_agentPool
=== RUN   TestOAuthClientsCreate_agentPool/with_valid_agent_pool_external_id
=== RUN   TestOAuthClientsCreate_agentPool/with_an_invalid_agent_pool
=== RUN   TestOAuthClientsCreate_agentPool/with_no_agents_connected
--- PASS: TestOAuthClientsCreate_agentPool (5.44s)
    --- PASS: TestOAuthClientsCreate_agentPool/with_valid_agent_pool_external_id (1.81s)
    --- PASS: TestOAuthClientsCreate_agentPool/with_an_invalid_agent_pool (0.43s)
    --- PASS: TestOAuthClientsCreate_agentPool/with_no_agents_connected (0.38s)
PASS
ok      github.com/hashicorp/go-tfe     5.911s
...

[brandonc]

Looks good

[brandonc]

It appears that you've also added the inverse relationship to the API (each agent pool has_many oauth-clients). What do you think about adding include_data = false to that new relationship in the API? Is there a good reason to serialize all of the oauth-clients associated with an agent pool?

[roleesinhaHC]

Agreed, added those changes https://github.com/hashicorp/atlas/pull/18747

[brandonc]

Some comments here would be appropriate

[uturunku1]

Thanks for walking me through your changes over the zoom meeting!

[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.