Shaders: rust-gpu integration to compile shader nodes to WGSL (#3097)

* shaders: shader compilation setup

* nix: use rustc_codegen_spirv.so from nix

* shaders: codegen for per_pixel_adjust shader nodes

* shaders: disable nodes needing bool

* shaders: `#[repr(u32)]` some enums

* shaders: add lint ignores from rust-gpu

* shaders: fix node-macro tests

* gcore-shaders: toml cleanup

* shader-nodes feature: put rust-gpu to wgsl compile behind feature gate

* shaders: fix use TokenStream2

* shaders: allow providing shader externally

* Update iai runner in workflow

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Co-authored-by: Timon Schelling <me@timon.zip>
Co-authored-by: Dennis Kobert <dennis@kobert.dev>

node-graph/graster-nodes/shaders/src/lib.rs

@@ -0,0 +1 @@
+pub const WGSL_SHADER: &str = include_str!(env!("GRAPHENE_RASTER_NODES_SHADER_PATH"));