Allow to use modifier + gamepad key as keybind

[VikingFromMoon]

Xbox elite controller allows to keybind ctrl, shift, alt, etc. to back buttons. Some people might use USB foot pedals and etc. In all such cases it would be make sense to allow to keybind ctrl, shift, alt + gamepad key without emulation being enabled.

[seblindfors]

It is possible to do this currently by using regular keystrokes as emulated paddle bindings, setting them up as mods and then swapping out the keystrokes for modifiers. A simple example is go to Interface > Bindings, set Emulate Paddle 1-4 to F1-F4, then go into Settings > Emulation and set your modifiers as you want them represented by icons. You can then remove the emulated paddle bindings F1-F4 as you won't be using them.