Check team ID format at plan

[tgermain]

Hi,

I stumble on a bug while authorizing team on a repository using github_team_repository.

The faulty code was something like :

resource "github_team_repository" "some_team_repo" {
  team_id    = "github_team.some_team.id"
  repository = "${github_repository.some_repo.name}"
  permission = "pull"
}

Simple bug : I forgot to interpolate github_team.some_team.id so the provider get the string github_team.some_team.id instead of a proper team ID.

It fails at apply with Unexpected ID format ("github_team.some_team.id"), expected numerical ID. strconv.ParseInt: parsing "github_team.some_team.id": invalid syntax

I think it's a kind of error you can catch at plan time easily.

This PR introduce a validation of team_id on the two resource using it as parameters : github_team_repository and github_team_membership.
It is a very basic check function that :

• try to cast the value as a string
• try to convert the string to an int

I tried the github provider on my faulty code it detects the error at plan time as expected.

[tracypholmes]

Hi, @tgermain! Thank you for submitting this PR. LGTM 🎉