Implement a "Pause Emulation" option & hotkey (#2428)

* Add a "Pause Emulation" option and hotkey

Closes Ryujinx#1604

* Refactoring how pause is handled

* Applied suggested changes from review

* Applied suggested fixes

* Pass correct suspend type to threads for suspend/resume

* Fix NRE after stoping emulation

* Removing SimulateWakeUpMessage call after resuming emulation

* Skip suspending non game process

* Pause the tickCounter in the ExecutionContext

* Refactoring tickCounter pause/resume as suggested

* Fix Config migration to add pause hotkey

* Fixed pausing only application threads

* Fix exiting emulator while paused

* Avoid pause/resume while already paused/resumed

* Cleanup unused code

* Avoid restarting audio if stopping emulation while in pause.

* Added suggested changes

* Fix ConfigurationState

Ryujinx/Config.json

@@ -60,7 +60,8 @@
   "hotkeys": {
     "toggle_vsync": "Tab",
     "screenshot": "F8",
-    "show_ui": "F4"
+    "show_ui": "F4",
+    "pause":  "F5"
   },
   "keyboard_config": [],
   "controller_config": [],