efl_ui_focus_manager: reduce the amount of relying on events
with this commit we are not replying on event invocations anymore, but
rather on direct flag observation in the focus manager itself.
This reduces the amount of events that are emitted as a consequence to
elements beeing marked dirty segnificantly.
startup time of elementary_test goes from 0.50 to 0.46s.
Differential Revision: https://phab.enlightenment.org/D12072