Graphql / Uplift collaborators data source

[patrickmarabeas]

Uplifts the collaborators data source to use v4 API

API surface has changed:

• Uses the organization specified to provider
• Takes a repository ID instead
• There is no affiliation functionality
• User object has been reduced significantly to include only relevant properties in the context of Terraform usage. Happy to hear opinions on this.

Example output:

collaborators = {
  "collaborators" = [
    {
      "email" = ""
      "is_site_admin" = false
      "login" = "patrickmarabeas"
      "name" = "Patrick Marabeas"
      "permission" = "ADMIN"
    },
  ]
  "id" = "MDEwOlJlcG9zaXRvcnkyMjk4NDU0NTg=/collaborators"
  "repository_id" = "MDEwOlJlcG9zaXRvcnkyMjk4NDU0NTg="
}

notes:

• This branch will be rebased as necessary
• Shared consts and functions will be abstracted int util_* files as required, I've simply included them within the one file for simplicity for the time being
• This constitutes a preliminary migration to the v4 API
• Tests will be written / updated once the API surface is nailed down