Add key layout for 8BitDo SN30 Pro gamepad

This CL adds Key Layout file for the 8BitDo SN30 Pro gamepad.
The 8BitDo SN30 gamepad has 4 layout modes:
  - Switch
  - Android (AKA D-Input)
  - Windows (AKA X-Input)
  - macOS

Switch, Windows and macOS modes are already covered by the Switch, Xbox
and DS4 key layout files. This CL adds the remaining mode.

Bug: 162043910
Test: Manually tested by launching Gamepad Tester APK and verifying that
      all the mappings are correct.
Change-Id: I41688c64188c0705d0286744a8f76a9268feca25