Add support for capacity aware modes to `google_compute_region_instance_group_manager

[upodroid]

Fixes: hashicorp/terraform-provider-google#8002

You also need to bump the API library to v0.36.

If this PR is for Terraform, I acknowledge that I have:

• Searched through the issue tracker for an open issue that this either resolves or contributes to, commented on it to claim it, and written "fixes {url}" or "part of {url}" in this PR description. If there were no relevant open issues, I opened one and commented that I would like to work on it (not necessary for very small changes).
• Generated Terraform, and ran make test and make lint to ensure it passes unit and linter tests.
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Release Note Template for Downstream PRs (will be copied)

compute: added `distribution_policy_target_shape` field to `google_compute_region_instance_group_manager` resource

[modular-magician]

Hello! I am a robot who works on Magic Modules PRs.

I have detected that you are a community contributor, so your PR will be assigned to someone with a commit-bit on this repo for initial review.

Thanks for your contribution! A human will be with you soon.

@slevenick, please review this PR or find an appropriate assignee.

[modular-magician]

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

Diff report:

Terraform GA: Diff ( 3 files changed, 35 insertions(+), 13 deletions(-))
Terraform Beta: Diff ( 3 files changed, 35 insertions(+), 13 deletions(-))

[modular-magician]

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

Diff report:

Terraform GA: Diff ( 3 files changed, 35 insertions(+), 13 deletions(-))
Terraform Beta: Diff ( 3 files changed, 35 insertions(+), 13 deletions(-))

[slevenick]

Please add possible values or a link to the documentation. Other comment about empty zones is more of a question

[slevenick]

Is it possible to set the target shape if the distribution policy zones are empty? We are opening the possibility of an empty list of zones here, which seems like it might cause problems

[upodroid]

I don't think so. Also, there a number of limitations that appear once you set target shape which are not validated in terraform.

https://cloud.google.com/compute/docs/instance-groups/regional-mig-distribution-shape

https://cloud.google.com/compute/docs/instance-groups/distributing-instances-with-regional-instance-groups#setting_a_policy_for_distributing_instances_across_zones

[modular-magician]

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

Diff report:

Terraform GA: Diff ( 3 files changed, 35 insertions(+), 13 deletions(-))
Terraform Beta: Diff ( 4 files changed, 36 insertions(+), 14 deletions(-))

[slevenick]

/gcbrun

Should work now that the API client is updated

[modular-magician]

I have triggered VCR tests based on this PR's diffs. See the results here: "https://ci-oss.hashicorp.engineering/viewQueued.html?itemId=168385"

[modular-magician]

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

Diff report:

Terraform GA: Diff ( 3 files changed, 35 insertions(+), 13 deletions(-))
Terraform Beta: Diff ( 4 files changed, 36 insertions(+), 14 deletions(-))

[slevenick]

Thanks!