Expose configured Bazel actions to the build proxy

[karim-alweheshy]

Summary

• Publish all proxy-owned BEP action completion events.
• Capture the exact configured product-action closure after a successful build.
• Keep the feature opt-in and exclude proxy metadata destinations from publishable receipts.

Stack

• Part of Feature Request: Have a build mode that leverages an XCBBuildService proxy for a more integrated experience #1953.
• 4 of 5 in the rules_xcodeproj build-proxy stack.
• Parent: the opt-in launcher PR.
• Next: action commands and cache provenance.

Validation

• Repository CI is green at this exact head.
• Live Xcode verifies configured and completed action reconciliation without duplicate rows.

Testing

Build a mapped target after a source change and on a no-change rebuild; verify configured plus completed product actions form one mutually exclusive union in the Xcode report.