Fix AsBindGroup derive, texture attribute, visibility flag parsing

[loganbenjamin]

Objective

• Fix the AsBindGroup texture attribute visibility flag parsing
• This appears to have been caused by a syn crate update which then the visibility code got updated
• Also I noticed that by default the vertex and fragment flags were on, so visibility(compute) would actually make the texture visible to vertex, fragment and compute shaders, I fixed this too

Solution

• Update flag parsing to use MetaList.parse_nested_meta function, which loads the flags into a Vec then loop through those flags
• Change initial visibility flags to use VisibilityFlags::default() rather than VisibilityFlags::vertex_fragment()

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[ThierryBerger]

wow good findings :o 👍 ; Would it be possible to catch this as a test ?

[loganbenjamin]

Good idea! I've added a test for the derive so that if the parsing fails it would now error.

It would be nice to improve the test to check if the visibility is correctly set but I'm not sure how to do that as I need to be able to call bind_group_layout which requires a RenderDevice. And I'm unsure how I would create/get a RenderDevice?

[cart]

Great work!