SDL3 Renderer support

[Ecialo]

I've made integration of sdl3 renderer. For sdl3 i've used the bindings by https://github.com/klukaszek/sdl3-hs
Demo window works with this renderer example.

It's totally not ready for merge, since the sdl3 bindings uses same namespace as sdl2 package. So the some cabal flag gymnastics is needed, which is looking ugly.
I'm totally need your advices how to make this more acceptable.

[Ecialo]

The namespace problem will be resolved after merging this

[Ecialo]

SDL3 was moved to the separate namespace, so it's good now.

[Ecialo]

Or not. Now I have a linking problems on the macos. Trying to solve it

[Ecialo]

Yeah. Linking on a mac does not work if sdl2 and sdl3 are installed at the same time and both cabal flags are used. For compatibility, I can turn off sdl3 cabal flag by default and add to the documentation how to enable it. What do you think about this solution?

[Ecialo]

The sdl3 flag now disabled by default

[dpwiz]

The CI builder is fubar for some reason and there's no retry button in sight. Can you amend the commit and force-push it?

[Ecialo]

@dpwiz done.

[dpwiz]

Some nix issues...

[Ecialo]

Can I help with this somehow?

[dpwiz]

Looks like niv should be used to tell nix about the SDL3 being used.
I wasn't able to build this with just Ubuntu libsdl3-dev package (too old, of course).