Promote WGPU to Full Support

[chyyran]

Naga needs to handle everything that slang-shaders throws at it for wgpu to earn a ✅. Unfortunately most of these changes need to be made upstream.

• [ ] Emit OpModfStruct instead of OpModf in glslang (in progress)
• [x] Polyfill inverse in Naga (waiting on wgpu release)

Things we can do for best-effort support on non-native platforms

• [x] Approximate WrapMode::ClampToBorder with WrapMode::ClampToEdge instead on non-native backends (#141)
• [x] Investigate whether we actually need TEXTURE_ADAPTER_SPECIFIC_FORMAT_FEATURES.
  • We don't.
• FLOAT32_FILTERABLE is already available on the web