Add convenience field support to Terraform, generate Network

[rileykarson]

Sorry for the # of changes! A few things had to happen for this PR.

Contained, roughly in order is;

• Add overrides for Terraform
• Add support for flattening objects
• Fix broken TF tests, test the actual complex cases (updating, legacy networks)
• Fix update for Network in api.yaml
• Clarify docs, remove the old resource-level message because it was outdated

Going from my definition of convenience fields;

convenience fields: When we take a nested object field and top-level it.
useful for nested objects with non-zero defaults.
example: BackendService connection_draining.draining_timeout_sec -> connection_draining_timeout_sec

This is adding support for the most useful subset, when a nested objects has been replaced entirely. Most? examples of convenience fields are a single field inside of an object, and this solution will unblock those cases. Support for nested convenience fields is a TODO, and something we should do if it's necessary, not just for fun.

I looked at using the overrides system to do this, and specifying convenience_name or something similar on the convenience field itself, but that approach didn't work well in the end. Our model for resource schemas relies pretty heavily on 1:1 mappings API <-> tool, and there are a lot of yaks to shave before that could be changed.

---

[all]

[terraform]

Generate google_compute_network using Magic Modules

[terraform-beta]

[ansible]

[inspec]

[nat-henderson]

This one is a challenge to review without the downstreams - I'll see if I can make sense of them when they come out.

[modular-magician]

Hi! I'm the modular magician, I work on Magic Modules.
This PR seems not to have generated downstream PRs before, as of 941b3f0.

Pull request statuses

No diff detected in Inspec.

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#509
depends: GoogleCloudPlatform/terraform-google-conversion#9
depends: hashicorp/terraform-provider-google#3203
depends: modular-magician/ansible#204

[nat-henderson]

If the network tests pass (and once you fix the quotes that travis is complaining about, and two minor tweaks on the beta / ga modules), I think I trust this to be right.

[rileykarson]

fyi @rambleraptor

[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, 0bd5d24.

Pull request statuses

terraform-provider-google-beta already has an open PR.
terraform-google-conversion already has an open PR.
terraform-provider-google already has an open PR.
Ansible already has an open PR.
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, 86ec298.

Pull request statuses

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

New Pull Requests

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