misc: chore: move Rainbow updating to a separate task started/stopped as needed

update gommon & use the Event class from it to allow easily clearing all handlers when the apphost exits to avoid leftover invalid event handlers in the rainbow event handler list.
More robust config application logic to ensure what needs to happen only happens once

src/Ryujinx.SDL2.Common/SDL2Driver.cs

@@ -168,8 +168,6 @@ namespace Ryujinx.SDL2.Common
                         HandleSDLEvent(ref evnt);
                     }
                 });
-                
-                Rainbow.Tick();
 
                 waitHandle.Wait(WaitTimeMs);
             }