praefect: Migrate sql-migrate sub-command

Migration of the 'sql-migrate' sub-command from the old implementation to the new approach with usage of the third party library. The invocation of the command remains the same, but it has more descriptive representation when help is invoked. Also, it is possible now to invoke help only for the sub-command to see more details about it and its usage.

Part of: #5001 (closed)