Add [D2DGeneratedPixelShaderDescriptor] attribute and use FAWMN

[Sergio0694]

Description

This PR adds the new [D2DGeneratedPixelShaderDescriptor] attribute to trigger the D2D1 source generator, and also includes a code fixer to automatically add it to shader types, along with several new diagnostic analyzers to provide useful errors.

API breakdown

namespace ComputeSharp.D2D1;

[AttributeUsage(AttributeTargets.Struct, AllowMultiple = false)]
public sealed class D2DGeneratedPixelShaderDescriptorAttribute : Attribute
{
}

[Sergio0694]

Hey @Youssef1313, feel free to take a quick look if you feel like it! I've added a new code fixer in this one 😄