* chore: apply exec rules after removal and use CWindowRule
* refactor: unregister exec rules after applying them
Remove the unused toRemove vector and defer unregistering exec rules
until after applyStaticRule/applyDynamicRule so exec rules are applied
before being removed from the rule engine.
Renames `misc:new_window_takes_over_fullscreen` into
`misc:on_focus_under_fullscreen` and implements the following behavior:
- By default, when a tiling window is being focused on a workspace where
a fullscreen/maximized window exists, respect
the `misc:on_focus_under_fullscreen` config variable.
