Implement a breaking change detection rule for protovalidate annotations

[doriable]

Feature

Some changes to protovalidate annotations should be considered breaking changes, e.g. removing a required annotation. We should implement a breaking change rule that checks for such conditions, similar to our PROTOVALIDATE lint rule.

[doriable]

This is currently not specced out. In the meantime, we have https://github.com/bufbuild/buf-plugin-protovalidate-strict