Better control on xDS deduplication based on protobuf

[lizan]

From discussion in #8231 (comment)

Key take aways:

• Prefer using version_info instead comparing new xDS delivered config with existing one, this also solves SDS onConfigUpdate ignores resource version #7676

• Add a UUID in ConfigSource for deduplication, instead of hashing ConfigSource proto to automatically dedup. This means RDS/SDS ConfigSource sent from LDS should be deduplicated at control plane.

[mattklein123]

Add a UUID in ConfigSource for deduplication, instead of hashing ConfigSource proto to automatically dedup. This means RDS/SDS ConfigSource sent from LDS should be deduplicated at control plane.

For discussion, what I said is slightly different, which is to make sure that every resource has a name to use for hashing and lookup, and then use the message differencer Envoy side to look for changes.