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

---------

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

node-graph/graster-nodes/src/blending_nodes.rs

@@ -141,6 +141,7 @@ fn blend<T: Blend<Color> + Send>(
 		Table<GradientStops>,
 		GradientStops,
 	)]
+	#[gpu_image]
 	over: T,
 	#[expose]
 	#[implementations(
@@ -149,6 +150,7 @@ fn blend<T: Blend<Color> + Send>(
 		Table<GradientStops>,
 		GradientStops,
 	)]
+	#[gpu_image]
 	under: T,
 	blend_mode: BlendMode,
 	#[default(100.)] opacity: PercentageF32,
@@ -165,6 +167,7 @@ fn color_overlay<T: Adjust<Color>>(
 		Table<GradientStops>,
 		GradientStops,
 	)]
+	#[gpu_image]
 	mut image: T,
 	#[default(Color::BLACK)] color: Color,
 	blend_mode: BlendMode,