[externals] Update to SDL3 (#3952)

Since the launch of the steam controller I think it's only best to push towards updating to SDL3 allowing for a wider range of controller support

I went ahead and started on getting it working. Everything here should be functional, I've personally tested it all on Arch Linux. Still untested on windows, so looking for feedback on that

Any feedback and help would be appreciated!

Main changes:
- Bump everything to SDL3
- Handle SDL3 audio and input
- Add steam controller support, including HD Rumble
- Improved battery reporting via the status icon by using real % rather than state alone

Co-authored-by: crueter <crueter@eden-emu.dev>
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3952
Reviewed-by: crueter <crueter@eden-emu.dev>
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Reviewed-by: Lizzie <lizzie@eden-emu.dev>

shell.nix

@@ -16,7 +16,7 @@ pkgs.mkShellNoCC {
     qt6.qtbase qt6.qtmultimedia qt6.qtwayland qt6.qttools
     qt6.qtwebengine qt6.qt5compat
     # eden-cli
-    SDL2
+    SDL3
     # optional components
     discord-rpc gamemode
   ];