Add hand invariant KeyCode for Modifier Keys

## What problem does this solve or what need does it fill?

It would be nice to have a variant of keycode that represent the Shift key regardless of if its left or right and the same for the other modifier keys

## What solution would you like?

Add a vaient to the keycode enum for Shift, Alt, Contol, and Super.
modify the system updating Input to check if the Left or Right Variant is pressed, or released and set invariant accordingly, this will need some thought as to order/priority since it would then be possible to be just press and just released at the same time if you alternate between left and right keys in the same frame

## What alternative(s) have you considered?

Nothing it's not that important just thought it would be neat

## Additional context

This would help with input managers since most of the time you don't care if its the left or right variant being pressed so they need to check both combinations or the user must specify that both work

Start by locating the KeyCode enum and the system that updates Input. Trace how left and right modifier keys are pressed and released, then determine how invariant Shift, Alt, Control, and Super states should behave when both variants change in one frame. Done means the enum and input state consistently expose the invariant modifier keys.

Written by the indexing model from the issue text.