Add PD APIs for RawKV GC #4865
Description
Development Task
Added new PD APIs to support RawKV GC as described by tikv/rfcs#90
- Merge RFC RFC:TiKV RawKV MVCC GC rfcs#90
- Merge kvproto pd: RawKV GC SafePoint API pingcap/kvproto#908 gcpb: renaming service group to key space pingcap/kvproto#915
Merge PD RawKV GC API ( Split from combined PR: #4866 )
- Merge PD Storage storage: Add APIs for RawKV GC #4937
- Merge PD Client client: Add APIs for RawKV GC #4943
- Merge PD Server