This patch adds API endpoint /column_family/autocompaction/{name}
that listen to GET and POST requests to pick and control table
background compactions.
To implement that the patch introduces "_compaction_disabled_by_user"
flag that affects if CompactionManager is allowed to push background
compactions jobs into the work.
It introduces
table::enable_auto_compaction();
table::disable_auto_compaction();
bool table::is_auto_compaction_disabled_by_user() const
to control auto compaction state.
Fixes#1488Fixes#1808Fixes#440
Tests: unit(sstable_datafile_test autocompaction_control_test), manual
1c444b7e1e