feat: add tfe_organization_token ephemeral resource

[ctrombley]

Description

Allow users to create an ephemeral resource for tfe_organization_token, so that the org token is not stored in the Terraform state file and can be handled securely and temporarily during Terraform operations.

Remember to:

• Update the Change Log
• Update the Documentation

Testing plan

1. Create a terraform configuration that has child module
2. In that module, try out a config similar to this:

ephemeral "tfe_organization_token" "example" {
  name   = "my-org-name"
}

output "my-org-token" {
  value       = ephemeral.tfe_organization_token.this.token
  ephemeral   = true
}

Then init and apply the configuration.
The state file should not include the ephemeral resource.

Output from acceptance tests

Please run applicable acceptance tests locally and include the output here. See testing.md to learn how to run acceptance tests.

If you are an external contributor, your contribution(s) will first be reviewed before running them against the project's CI pipeline.

$ TESTARGS="-run TestAccOrganizationTokenEphemeralResource" make testacc

...

[uturunku1]

Should we add a release note about this new ephemeral resource? I had forgotten to do that for the agent token. But I plan to include it in my upcoming PR.

[ctrombley]

Should we add a release note about this new ephemeral resource? I had forgotten to do that for the agent token. But I plan to include it in my upcoming PR.

Addressed in 38b2374.

[uturunku1]

The changes look good! Do the tests need to be updated?

[brandonc]

Suggested change

	be written to state. Since organization tokens are singleton resources, using this ephemeral resource will replace any existing organization token.
	be written to state. Since organization tokens are singleton resources, using this ephemeral resource will replace any existing organization token, including those managed by `tfe_organization_token`.

[ctrombley]

Addressed in 93f913b.

[brandonc]

I think this is optional because it probably can use provider config.

[ctrombley]

Good catch, addressed in 93f913b.