Material system: rework to use Sokol's yaml output for shader generation

The current Material system is bulky to work with because the uniform buffer locations can change depending on the shader's content, and it doesn't support modding well as right now it requires the shaders to be generated as Zig code.

The author of Sokol said about this problem:

_I think the best option for that use case is to use the bare_yaml output in sokol-shdc. The resulting YAML reflection file should be easy enough to parse without a full yaml parser at hand, and the shader-blobs themselves can be runtime-loaded._