Connection handling of "lastInsertId" does not handle fixed identifiers correct

[glady]

The same issue like #19. On Insert a row over function insert, the connection tries to remember last inserted id. This will not work correctly for non-autoincrement primary keys and possibly also fixed ids like in #20

[glady]

Corresponding code was introduced with commit on #6

[glady]

Added Tests:

• working well for Autoincrement columns
• not supported on not-autoincrement columns by database itself: e.g. https://dev.mysql.com/doc/refman/8.0/en/information-functions.html#function_last-insert-id