New snapshotting mode for recovery of DB history topic

Our organization spoke with rhauch last week to discuss the options for recovering the db-history topic should it be lost or corrupted in some way.

Our schemas do not change very often (every couple weeks at most), so we are in a situation where if we lost the db-history topic, we could theoretically use the schema_only mode to regenerate this topic. However, when we tried this, the snapshot stamps the current binlog position for all the generated DDL statements. So when we restart the connector pointing to the new db-history topic, it cannot pickup at the position it left off because it has no DDL history yet at this position.

So we discussed the possibility of a implementing "forced" schema_only mode. This would re-snapshot the schema only for a running connector, and set the binlog position for the generated DDL to the current position of the connector.

This will only work in a use case where we know there have been no effective DDL changes during the recovery period.