DB-Level Changefeed: Create PTS record per table during changefeed planning

[aerfrei]

Write these PTS records when planning the changefeed. Should be similar to current implementation except a) we create more records and b) multiple records need to be added to the progress proto.

Epic: CRDB-1421

Jira issue: CRDB-51236

Epic CRDB-1421

[blathers-crl]

cc @cockroachdb/cdc