Controller Remapping GUI v2 (#3144)

* Remapping GUI V2 - initial commit

* Unmap button with escape key

* Allow combination inputs

* Use separate class for SDL event signals so that i can work with the SDL window event loop

* Automatically pause game when GUI open to better manage event queue

* Move sd;_gamepad_added event from remap object to GUI object to avoid conflicts with sdl window

* Use signals on button/trigger to release to make GUI more responsive

* pause game while KBM window is open for consistency

* don't check gamepad when game is running to avoid conflicts

* Block all other sdl events instead of pausing game, automatic parse inputs after saving

* Don't block window restored or window exposed cases

* Properly exit event loop thread on exit

CMakeLists.txt

@@ -1068,6 +1068,8 @@ set(QT_GUI src/qt_gui/about_dialog.cpp
            src/qt_gui/gui_settings.h
            src/qt_gui/settings.cpp
            src/qt_gui/settings.h
+           src/qt_gui/sdl_event_wrapper.cpp
+           src/qt_gui/sdl_event_wrapper.h
            ${EMULATOR}
            ${RESOURCE_FILES}
            ${TRANSLATIONS}