sql: fix grammar for foreign key actions

SQLite grammar implementing foreign keys parsing is quite compact, but
on the other hand it allows to define ON DELETE and ON UPDATE actions
multiple times. For instance:

... REFERENCES t ON DELETE UPDATE ON DELETE RESTRICT;

It makes no sense and contradicts original ANSI syntax. So, lets rework
it a bit. Firstly, MATCH clause must come first, so we place it in
independent rule. Then we remove ON INSERT clause, since there is no
such opportunity at all. Finally, we have only 4 options to expose
refargs (i.e. grammar rule to parse FK actions): ON UPDATE, ON DELETE,
ON UPDATE ON DELETE, ON DELETE ON UPDATE. That's it.

Closes #3475