ScyllaDB agent changelog

Added the source lag probe, reporting the unread change backlog and how far behind the last read transaction is;

CQL write parameters are bound in the order the query declares them;

CQL binding fixes on the insert-conflict path (UPSERT / SKIP / FAIL);

Improved support for enhaced columns discovery (precision, lenght, scale);

Snapshot performance enhancements;

Agent compatibility upgrade to Gluesync 2.2;