Shader color conversion

[lynn-lumen]

Objective

• Fixes #12201

Solution

• Adds color_conversion.wgsl containing methods for converting between all bevy_color color types in shader code.
  • Please note that this shader is contained in the bevy_render crate (not bevy_color), as this would introduce cyclic dependency.
  • All conversion methods are equivelant to their Rust versions in bevy_color.
• Currently all colors can be converted from and to LinearRgb(a) and to all internediate steps according to the diagram in bevy_color
• The conversion methods can be imported in any WGSL shader using e.g. #import bevy_render::color_conversion::linear_rgba_to_xyza

Additional information

I am not sure how discoverable WGSL imports are. The examples demonstrate some use cases, but if available WGSL imports are documented somewhere, I have missed that.

[lynn-lumen]

I'm not familiar enough with WGSL to comment on how good the exact implementation is, but is there a way you could add tests for these methods that compare to the Rust implementations in bevy_color? Since bevy_color is already independently implemented and tested against palette, if the conversions here agree there, I'd say it's good to go.

I believe it would be the first instance of such a testing setup, and would involve a decent bit of setup for the boilerplate of a test, so I'm not sure if you'd want to add that to this PR. I think there would be value in such a testing framework for other utility shaders as well, but again I'm not certain.

I like this idea, but I think, this is way beyond the scope of this PR. If it's fine with you, I would look into this and add such tests in a follow up PR

[bushrat011899]

I think that's perfectly fine, I agree it's quite a bit of work!

[IceSentry]

Can you fix the conflicts?

Also, what's the use case for this? Shouldn't color conversion be done before it ends up on the gpu?