[Migrated] Make error messages more human

Issue automatically imported from old repo: https://github.com/EmbarkStudios/rust-gpu/issues/1139
Old labels: t: enhancement
Originally creatd by LegNeato on 2024-03-26T15:34:16Z

Currently the rust-gpu error messages are super obtuse and require understanding of both graphics programming and the underlying apis like vulkan. They are not written for humans to understand and while useful don't meet the high bar that rustc has set. For example, this is the error message when you use a built-in variable that is only valid for vertex shaders in a fragment shader:

error: error:0:0 - [VUID-Position-Position-04318] Vulkan spec allows BuiltIn Position to be used only with Vertex, TessellationControl, TessellationEvaluation or Geometry execution models. ID <15> (OpLoad) is referencing ID <2> (OpVariable) which is decorated with BuiltIn Position in function <1> called with execution model Fragment.
         %15 = OpLoad %v4float %frag_coord

Instead of an issue this might be more a project, let me know if you want me to write a RFC with concrete suggestions and a plan to make these great.

The issue names no files, tests, or entry points. Start by reviewing the current diagnostic path and the example Vulkan error, then define an RFC with concrete suggestions and a plan for human-readable shader errors; completion would require an agreed project scope and implementation plan.