Add alternate keybind slots for Osu!Taiko Right(Center) and Right(Rim)

[Emmiebacon5]

For some reason, alternate keybindings are allowed for the left-side Don and Kat, but not Right side Don and Kat.

This means if i wanted to switch from my keyboard to, say, a controller or my taiko drum controller, i have to go into the settings and completely remap, and then remap again when I go back to using a keyboard instead of just using alternate keybindings like every other game mode.

[peppy]

#38313