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/node-macro/src/codegen.rs

@@ -295,6 +295,7 @@ pub(crate) fn generate_node_code(parsed: &ParsedNodeFn) -> syn::Result<TokenStre
 
 	let cfg = crate::shader_nodes::modify_cfg(attributes);
 	let node_input_accessor = generate_node_input_references(parsed, fn_generics, &field_idents, &graphene_core, &identifier, &cfg);
+	let shader_entry_point = attributes.shader_node.as_ref().map(|n| n.codegen_shader_entry_point(parsed)).unwrap_or(Ok(TokenStream2::new()))?;
 	Ok(quote! {
 		/// Underlying implementation for [#struct_name]
 		#[inline]
@@ -384,6 +385,8 @@ pub(crate) fn generate_node_code(parsed: &ParsedNodeFn) -> syn::Result<TokenStre
 				NODE_METADATA.lock().unwrap().insert(#identifier(), metadata);
 			}
 		}
+
+		#shader_entry_point
 	})
 }
 
@@ -586,6 +589,7 @@ fn generate_register_node_impl(parsed: &ParsedNodeFn, field_names: &[&Ident], st
 	})
 }
 
+use crate::shader_nodes::CodegenShaderEntryPoint;
 use syn::visit_mut::VisitMut;
 use syn::{GenericArgument, Lifetime, Type};