Treat Left and Right Ctrl/Shift/Alt keys as separate inputs

[SirYodaJedi]

Currently binding either left or right Ctrl, Shift, or Alt to a button will treat both left and right versions of that key as both being bound to said button. This is a bit problematic if you want to bind these keys to different buttons.

For example, my ideal control scheme that I'd be comfortable with for 90% of GBA games would be such, which isn't possible without decoupling left and right shift:

D-Pad: Arrow keys
A: X
B: Z
L: LCtrl
R: LShift
Start: Enter
Select: RShift

Currently using v0.10.4 (64-bit, portable) on Windows 10 2h22.

[endrift]

Duplicate of #1766. I'm not sure it's possible with the framework I'm using, but it's definitely something I'd like to do if it is.

[SirYodaJedi]

Oh, sorry, must've missed the other when searching.

[endrift]

It wasn't easy to find myself, tbf