Gampad support for classic

Is it possible to have the gamepad support for classic also?

I have tested it adventure, i think its good enough.

And it would be great to be able to be mapped manually (Custom Key Mapping), because i'm thinking on using Joycon as the controller.

Start by examining how gamepad support works in Adventure and how Custom Key Mapping is exposed. Trace the input handling for Classic, then define the smallest change that enables gamepad use and manual Joy-Con mapping there; done means both controls work reliably in Classic.

Written by the indexing model from the issue text.