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?

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Note

Medium Risk
Moderate risk because it changes protobuf source inputs and adds large third-party proto definitions, which can affect code generation/build behavior and introduce compilation conflicts.

Overview
Updates temporal-serviceclient proto generation to include a new src/main/proto-thirdparty source directory.

Vendors the protoc-gen-openapiv2 OpenAPI v2 option protos (annotations.proto, openapiv2.proto) so newer cloud-api protos can compile against these dependencies.

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