rgw/dedup: full object dedup continued work

rgw/dedup: full object dedup continued work

Moved all control objects (EPOCH, WATCH, Tokens) to default.rgw.control
pool.
Add dedup_pool to RGWZoneParams to make the name unique across zones
rgw.dedup pool is created on dedup start and removed when the scan is
over

report duplicated space after dedup because of the head-object
report potential dedup for smaller objects (64KB-4MB)
added tests for the new reporting facilities

Signed-off-by: Gabriel BenHanokh <gbenhano@redhat.com>