compaction.hh is one of our heavy headers, but some users just want to
use information on it about how to describe a compaction, not how to
perform one.
For that reason this patch splits the compaction_descriptor into a new
header.
The compaction_descriptor has, as a member type, compaction_options.
That is moved too, and brings with it the compaction_type. Both of those
structures would make sense in a separate header anyway.
The compaction_descriptor also wants the creator_fn and replacer_fn
functions. We also take this opportunity to rename them into something
more descriptive
Signed-off-by: Glauber Costa <glauber@scylladb.com>
3972628fc0