Add SDL3

[Ghabry]

To not break too much stuff I suggest to do this in multiple steps:

1. Add SDL3 and keep SDL2 for now. They dont have any file conflicts so this is safe to do
2. Change the default in the Player to SDL3

• For now keep emscripten (canvas scale issues) and Android (crashes) on SDL2

3. When everything is ported remove SDL2 in another PR to buildscripts