MDEV-12302: Execute triggers for foreign key updates/deletes [WIP]

[Simoffsky]

• [x] The Jira issue number for this PR is: MDEV-______

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[vuvova]

we don't really want to push more of the server logic inside InnoDB. Besides triggers cascading updates/deletes have problems with CHECK constraints, unique constraints WITHOUT OVERLAP and USING HASH, online ALTER TABLE and likely other features.

The idea of MDEV-31942 was to let InnoDB inform the server via some kind of a callback when it performs cascading changes and the server could then do what is needed — triggers, checks, logging, statistics, whatever.

[FooBarrior]

@Simoffsky just to clarify what @vuvova means, we'll extract the maria_table->triggers->process_triggers call into the sql-layer function (somewhere in sql_class.cc). We do want to execute triggers from innodb cascade changes!