Set resource-creator-email tag to GitHub-Actions

[GaryGSC]

We have a lot of noise in our Terraform plans because we evidently have some background process adding this tag to our resources. Let's add that tag ourselves to cut down on the noise.

[GaryGSC]

Clearly this introduces an opinion (#214), but this is pretty non-intrusive and tags are free.

[GaryGSC]

Example:

  # module.app.module.my_fargate_api.aws_ecs_cluster.new_cluster[0] has changed
  ~ resource "aws_ecs_cluster" "new_cluster" {
        id                 = "arn:aws:ecs:us-west-2:***:cluster/hw-fargate-api-dev"
        name               = "hw-fargate-api-dev"
      ~ tags               = {
          + "resource-creator-email" = "GitHub-Actions"
        }
      ~ tags_all           = {
          + "resource-creator-email" = "GitHub-Actions"
            # (3 unchanged elements hidden)
        }
        # (2 unchanged attributes hidden)

        # (1 unchanged block hidden)
    }