Add field for azure private connectvity rule

[david049]

What was changed

Adding support for azure CR

Why?

Checklist

1. Closes

2. How was this tested:

3. Any docs updates needed?

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Note

Low Risk
Additive protobuf API change with explicit min-version tagging; no runtime logic in this diff, though downstream services must honor the new field for Azure private connectivity.

Overview
Bumps the API release to v0.18.0 and extends PrivateConnectivityRule so Azure private connectivity can be represented alongside existing AWS/GCP rules.

Adds azure_pe_resource_id (field 5, gated at min_version=v0.18.0) for the customer’s Azure Private Endpoint ARM resource ID, which is required for Azure private rules. Comments on connection_id, region, and gcp_project_id are updated to spell out per-cloud behavior (including that Azure connection_id is infra-populated via PPv2 LinkID, and Azure region examples like azure-eastus).

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