Add UHID gamepad support

Similar to UHID keyboard and mouse, but for gamepads.

Can be enabled with --gamepad=uhid or -G.

It is not enabled by default because not all devices support UHID
(there is a permission error on old Android versions).

PR #5270 <https://github.com/Genymobile/scrcpy/pull/5270>

app/data/bash-completion/scrcpy

@@ -26,6 +26,7 @@ _scrcpy() {
         -e --select-tcpip
         -f --fullscreen
         --force-adb-forward
+        -G
         --gamepad=
         -h --help
         -K
@@ -129,7 +130,7 @@ _scrcpy() {
             return
             ;;
         --gamepad)
-            COMPREPLY=($(compgen -W 'disabled aoa' -- "$cur"))
+            COMPREPLY=($(compgen -W 'disabled uhid aoa' -- "$cur"))
             return
             ;;
         --orientation|--display-orientation)