More features in blocking mode, ulid() is created per feed

[dss-vipps]

• Remove changefeed.ulid(). However, support for such functions already created is kept, they will still work, but new ones will not be created in new installations.
• Instead, changefeed.[ulid:yourschema.YourTable]() is made available
• Also, changefeed.[lock:*] gets some new arguments, and if you only need a single ulid you can just grab it from there

These changes are done because the previous interface didn't allow writing to more than one feed in one database transaction; this quickly broke down in real world usage.

[dtitov]

My SQL knowledge is not enough to check the validity of the script itself, but I get the rationale behind this change (after the discussion in Slack) and the described usage seems OK 👍

[dss-vipps]

Rebased