rgw/notifications: support metadata filter in CompleteMultipartUpload events

 rgw/notifications: support metadata filter in CompleteMultipartUpload events

 Fixes: https://tracker.ceph.com/issues/51261
Signed-off-by: Yuval Lifshitz <ylifshit@redhat.com>
(cherry picked from commit 93b9f0fb77ca5ed0b5c89d45229732850e0a0c49)

Conflicts:
	src/rgw/rgw_notify.h
	src/rgw/rgw_op.cc
	src/rgw/rgw_sal.h
	src/rgw/rgw_sal_rados.cc
	src/rgw/rgw_sal_rados.h
	src/test/rgw/bucket_notification/test_bn.py

Cherry-pick notes:
- differences due to renaming of rgw::sal::RGWObject to rgw::sal::Object
- differences due to use of RadosNotification in master and reservation_t in Pacific