[ticket/13006] Add variables to the 'core.modify_quickmod_actions' event

Add $quickmod and $action variables
for the 'core.modify_quickmod_actions' event trigerring
to avoid of using global operator in corresponding extensions.

PHPBB3-13006
Merge pull request #2903 from rxu/ticket/13006

[ticket/13006] Add variables to the 'core.modify_quickmod_actions' event

* rxu/ticket/13006:
  [ticket/13006] Add variables to the 'core.modify_quickmod_actions' event