Handle deleted: prefix when deduplicating IAM member map

[slevenick]

I thought this wasn't going to be an issue, but it seems to be. We run all IAM members through this function to deduplicate them case insensitively, but new deleted IAM principals cause issues with serviceAccount members as we split on the : character that is prefixed to the deleted principal. This causes us to downcase serviceAccount which is case sensitive, so when we send the IAM policy back to the server it doesn't recognize serviceaccount as serviceAccount and throws a 400.

This causes issues because even when we specify a single IAM member, we retrieve the IAM policy for the resource and run it through this method. We send back the resulting IAM policy (after our addition) which has been modified via downcasing by this method.

The fix checks for deleted: as a prefix and only downcases the principal value not the type

Release Note Template for Downstream PRs (will be copied)

`iam`: Fixed a bug that causes badRequest errors on IAM resources due to deleted serviceAccount principals

[modular-magician]

Hi! I'm the modular magician, I work on Magic Modules.
I see that this PR has already had some downstream PRs generated. Any open downstreams are already updated to your most recent commit, d1ef609.

Pull request statuses

No diff detected in Ansible.

New Pull Requests

I built this PR into one or more new PRs on other repositories, and when those are closed, this PR will also be merged and closed.
depends: hashicorp/terraform-provider-google-beta#1501
depends: GoogleCloudPlatform/terraform-google-conversion#288
depends: hashicorp/terraform-provider-google#5142
depends: modular-magician/inspec-gcp#279

[modular-magician]

Hi! I'm the modular magician, I work on Magic Modules.
I see that this PR has already had some downstream PRs generated. Any open downstreams are already updated to your most recent commit, a814b6f.

Pull request statuses

terraform-provider-google-beta already has an open PR.
No diff detected in terraform-google-conversion.
terraform-provider-google already has an open PR.
No diff detected in Ansible.
No diff detected in Inspec.

New Pull Requests

I didn't open any new pull requests because of this PR.

[danawillow]

LGTM pending clean magician run

[modular-magician]

Hi! I'm the modular magician, I work on Magic Modules.
I see that this PR has already had some downstream PRs generated. Any open downstreams are already updated to your most recent commit, 9f7364e.

Pull request statuses

terraform-provider-google-beta already has an open PR.
No diff detected in terraform-google-conversion.
terraform-provider-google already has an open PR.
No diff detected in Ansible.
No diff detected in Inspec.

New Pull Requests

I didn't open any new pull requests because of this PR.

[modular-magician]

Hi! I'm the modular magician, I work on Magic Modules.
I see that this PR has already had some downstream PRs generated. Any open downstreams are already updated to your most recent commit, d4de503.

Pull request statuses

terraform-provider-google-beta already has an open PR.
No diff detected in terraform-google-conversion.
terraform-provider-google already has an open PR.
No diff detected in Ansible.
No diff detected in Inspec.

New Pull Requests

I didn't open any new pull requests because of this PR.