applets/controller: Modify heuristic to account for certain games

Now left and right joycons have the same priority (meaning both needs to be supported by the game).

Explanation of the new heuristic:
Assign left joycons to even player indices and right joycons to odd player indices.
We do this since Captain Toad Treasure Tracker expects a left joycon for Player 1 and a right Joycon for Player 2 in 2 Player Assist mode.