[YDBOcto#929] Lowercase SQL IDs

As part of YDBOcto#929 (closed), SQL identifier storage in Octo is being switched to lowercase to allow compatibility with Postgres clients (PGAdmin and Ngpsql (used by PowerBI)). More details are in the linked issue.

This commit changes the references to the object names (used in the keys(...) expression) to be lowercase, as they won't reference an existing object anymore after YDBOcto#929 (closed).

Version bumped to v1.9.