[ticket/12561] Add "after" check to schema_generator for columns_add
* PayBas/ticket/12561:
[ticket/12561] Reworked tests by nickvergessen
[ticket/12561] Added tests for "after last", "after missing" and "empty"
[ticket/12561] Add check to see if "after" column actually exists
[ticket/12561] Added test for "after"
[ticket/12561] Add "after" check to schema_generator for columns_add
* github-nickvergessen/ticket/12282:
[ticket/12282] Update new references
[ticket/12282] Update container db mock
[ticket/12282] Add new line at EOF of the interface
[ticket/12282] Use interface for type hinting
[ticket/12282] Use {@inheritDoc} for inherited methods
[ticket/12282] Add Interface for DBAL drivers
Make sure we throw an exception in the schema generator if we come across an
unresolvable dependency. Otherwise we'll get stuck in a infinite loop that
needs to be cancelled by the user or the maximum execution time.
PHPBB3-12362
