Fail MongoDB start when oplog is used for MongoDB 5+

The connector should upon start check the version of the database it is connected to.
In case of MongoDB 5 and later it should reject to start if the capture mode is set to oplog.

This needs a code refactoring as both snapshot and streaming source has their own duplicated way how to connect to the database.

This should be pulled up somehere to the task level so the code duplication will be removed and the connection and version check could be established at connector start.