Move ShaderCache shader defs into a resource

[ProfLander]

Objective

• NO_STORAGE_BUFFERS_SUPPORT, NO_ARRAY_TEXTURES_SUPPORT and SIXTEEN_BYTE_ALIGNMENT are injected by ShaderCache::get, which occurs after pipeline specialization, and therefore after Material or Material2d get the chance to inspect or mutate them in their respective specialize functions.

• Fixes Material::specialize is provided an incomplete set of engine-sourced shader definitions #8190

Solution

• Move said defs into a new BaseShaderDefs newtype resource, and have consuming pipelines retrieve it in their FromWorld implementation for use during specialization.

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Changelog

• Removed late def injection from ShaderCache
• BaseShaderDefs resource implemented to hold affected defs, inserted into the render world by RenderPlugin
• Extended existing consumers of the related defs with logic to fetch data from BaseShaderDefs in FromWorld, and use it in lieu of constructing an empty defs vec in specialize:
  • MeshPipeline
  • Mesh2dPipeline
  • PrepassPipeline
  • GizmoPipeline

Migration Guide

This is a non-breaking change, but future pipeline implementors should be made aware that the defs in question should be manually sourced from the ECS.

[tychedelia]

This helps clean up the ShaderCache code itself and I like having these in a default location. The disadvantage now is that users of pipeline specialization don't get these "for free." Overall seems like a good change since it helps prevent an annoying error, but I'd like more documentation somewhere about what our "base" shader defs are for users who might want to use them for consistency.

[mockersf]

superseded by e9e11cd from #20330