Add cheat support

[Michanne]

https://forums.pcsx2.net/Thread-Spectabis-Advanced-Game-Launcher-Frontend?pid=574069#pid574069

Add a menu item in right-click as "Cheats" where a user can manage their cheats for the particular game in a neat UI.

These Cheats will be saved as normal into PCSX2 cheat directory

Feature should also be able to read the cheat files already present in that directory and display any pre-existing cheats.

There should also be support for saving all cheats and having the option to turn them off/on again whenever the user wishes, and it would be great if all available cheats for a game (from some source) were already available when user loads their game.