Adds typed uniforms to ShaderMaterial and RawShaderMaterial

[haxiomic]

I've been using this for years in my own projects where I use custom shaders often. Typing uniforms makes working with these classes much nicer

let shader = new ShaderMaterial({ uniforms: { example: new Uniform(3), ... }, ... });

// typed correctly!
shader.uniforms.example.value = 4

This does not change the behaviour of existing code because uniform types default to any

[haxiomic]

I'll add Defines types before this is complete