The recent change assumed that Keybinding.keyCode was the actual keycode but it
is actually the keycode excluding the modifier. This change gets around that by
exposing a Keybinding.isModifierKey function which compares the actual
keybinding against the keybinding with a modifier key binary mask applied.

Fixes #16833

- Show warnings only once
- Open resource editor to show warnings

fixes #16640

fixes #16431

fixes #16625

fixes #16716
fixes #16750

This reverts commit f288e3ae.

fixes #16576

fixes #16657