Add information about failing member into the error message

[modular-magician]

When working with dynamically generated list of IAM resources, the error message is not that useful:

Error: invalid value for member (IAM members must have one of the values outlined here: https://cloud.google.com/billing/docs/reference/rest/v1/Policy#Binding)

  with module.projects-iam["service1"].google_project_iam_member.shared_vpc_host_iam["rw"],
  on ../project/shared-vpc.tf line 131, in resource "google_project_iam_member" "shared_vpc_host_iam":
 131:   member     = each.value

It makes hard to actually identify offending value. Returning failing member value helps to narrow down, which value was passed incorrectly.

See Write release notes for guidance.

iam: added member value to the error message when member validation fails for google_project_iam_*

Derived from GoogleCloudPlatform/magic-modules#13146