Named bindgroups

[antonWetzel]

Closes #88

This MR adds 2 flags to the WriteOptions.
This is just an experiment, how the generated bindings for bind groups could look like.
The code generation with the flags disabled is unchanged.

named_bind_groups

Name the bind groups not (BindGroup0, BindGroup1, ...), but (BindGroupCamera, BindGroupTextureSampler, ...).

Example

@group(0) @binding(0)
var<uniform> camera: Camera;
@group(0) @binding(1)
var<uniform> settings: GlobalSettings;

@group(1) @binding(0)
var texture: texture_2d<f32>;
@group(1) @binding(1)
var sampler: sampler;

struct BindGroupCameraSettings { /*...*/ }
struct BindGroupTextureSampler { /*...*/ }

shared_bind_groups

Place bind groups in a common module where possible.

Example

@group(0) @binding(0)
var<uniform> shared_camera: Camera;
@group(0) @binding(1)
var<uniform> shared_settings: Settings;

mod shared {
    struct BindGroupCameraSettings { /*...*/ }
}

Other changes

• Use iterators in the quote!-macro without collecting into a Vec
• Remove pathdiff dependency