Use ResourceIamPolicy for google_project_iam_policy

[rileykarson]

Fixes hashicorp/terraform-provider-google#777

Release Note Template for Downstream PRs (will be copied)

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 4 files changed, 111 insertions(+), 189 deletions(-))
Terraform Beta: Diff ( 4 files changed, 46 insertions(+), 189 deletions(-))

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 5 files changed, 111 insertions(+), 189 deletions(-))
Terraform Beta: Diff ( 5 files changed, 46 insertions(+), 189 deletions(-))

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 5 files changed, 112 insertions(+), 189 deletions(-))
Terraform Beta: Diff ( 5 files changed, 47 insertions(+), 189 deletions(-))

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 5 files changed, 47 insertions(+), 189 deletions(-))
Terraform Beta: Diff ( 5 files changed, 47 insertions(+), 189 deletions(-))