Support compaction operation to compact only one rowset.
After the modification, the last rowset of the tablet will
also be compacted.
At the same time, we added a `segments_overlap_pb` field to
the rowset meta. Used to describe whether the segment data
in the rowset overlaps. This field is set by `rowset_writer`.
Initially UNKNOWN for compatibility with existing data.
In addition, the version hash of the rowset generated after
compaction is directly set to the version hash of last rowset
participating in compaction, to ensure that the tablet's
version hash remains unchanged after compaction.
1421a9be41