Add an option to exact-match keybindings #1493
Fixes ppy/osu#2315 .
The cause was that
I still think there is some validity to passing OnKeyDown/OnAction simultaneously , but that's a future consideration and wouldn't negate this change.
Because all OnPressed methods returned false, the input was propagating down to all buttons, which resulted in incorrect values for SimultaneousMode = None. E.g. SimultaneousMode = None with Ctrl+A: 1. Pass down Ctrl+A, the Ctrl+A button responds to it but doesn't handle it. 2. Since Ctrl+A wasn't handled, A is passed down. A button gets lit up, Ctrl+A button gets released due to the simultaneous mode.