MySQL connector may not read database history to end

The MySQL connector upon startup attempts to read the database history topic to the end, but the current logic will stop early if there are timeouts or other issues. The logic should change to:

1. Read the last offsets for the assigned topic partition(s) with consumer.endOffsets(consumer.assignment())
2. Consume the messages while the offset of any message is less than that end offset for the corresponding partition.

See Connect's KafkaBasedLog for an example of how this is done.