Update Temporal Cloud-API to v0.12.0

[chndler]

What was changed

• Update Temporal cloud-api to v0.12.0
• Add protoc-gen-openapiv2 protos to support api-cloud v0.12.0

Why?

Checklist

1. Closes

2. How was this tested:

3. Any docs updates needed?

---

Note

Medium Risk
Medium risk because it changes protobuf source sets and adds large third-party proto schemas, which can affect code generation outputs and build compatibility.

Overview
Updates temporal-serviceclient's protobuf build to also compile protos from a new src/main/proto-thirdparty source directory.

Vendors the protoc-gen-openapiv2 option protos (annotations.proto, openapiv2.proto) so cloud-api v0.12.0 protos that import these files can compile without external proto dependencies.

^{Written by Cursor Bugbot for commit 9301c7e. This will update automatically on new commits. Configure here.}

[CLAassistant]

All committers have signed the CLA.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}