Keep the generated proto code in step with platform releases

We should make sure our generated ts files are up to date in a variety of ways:

1. Make sure to check out the protos using the latest version of platform/protocol version imported by 'current supported' version of platform/service
2. Add Gencode update check as part of prepack step
3. Add gencode up-to-date check to ci
4. Validate work with round trip test with platform/service
