The combo box for select actions should be searchable

[Czaki]

We may use QSearchableComboBox from superqt to simplify actions selection

midi-app-controller/midi_app_controller/gui/utils.py

Line 82 in cd96bf0

class ActionsQComboBox(QComboBox):

[jni]

@Czaki The current one searches already (at least for me on macOS) but doesn't filter.

[jni]

(agree this would be an improvement)