Task manager's tasks covering scrub compaction on top,
shard and table level.
For this levels we have common scrub tasks for each scrub
mode since they share code. Scrub modes will be differentiated
on compaction group level.
Closes#13694
* github.com:scylladb/scylladb:
test: extend test_compaction_task.py to test scrub compaction
compaction: add table_scrub_sstables_compaction_task_impl
compaction: add shard_scrub_sstables_compaction_task_impl
compaction: add scrub_sstables_compaction_task_impl
api: get rid of unnecessary std::optional in scrub
compaction: rename rewrite_sstables_compaction_task_impl
bb62038119