feat: add tfe_team_token ephemeral resource

[shwetamurali]

Description

Allow users to create an ephemeral resource for tfe_team_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:

resource "tfe_team" "example" {
  organization = "my-org-name"
  name = "team-test"
}

ephemeral "tfe_team_token" "example" {
  team_id = tfe_team.example.id
}

output "my-team-token" {
  value       = ephemeral.tfe_team_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 TestAccTeamTokenEphemeralResource" make testacc

...

[uturunku1]

We are just missing the release note, but it works great!

[ctrombley]

We are just missing the release note, but it works great!

Updated in 493c819.