Shaders: runtime and shader node codegen (#2985)

* shader-rt: initial

* shader-rt: fix recursion when generating shader node

* shader-rt: replace gpu node's args and ret types with `Raster<GPU>`

* shader-rt: properly cfg out the gpu node

* shader-rt: fix `impl Context` in the wrong places

* shader-rt: disable gpu blend node, needs two images

* shader-rt: connect shader runtime

* shader-rt: pass WgpuExecutor by reference

* shader-rt: correct bindings with derpy arg buffer

* shader-rt: manual pipeline layout, fixing errors when bindings got DCE'd

* shader-rt: correct RT format, working invert gpu node

* shader-rt: cleanup codegen with common sym struct

* shader-rt: correct arg buffer handling

* shader-nodes feature: put shader nodes behind feature gate

* shader-nodes feature: rename any `gpu_node` to `shader-node`

* shaders-rt: fix wgpu label name

* shaders-rt: explain fullscreen_vertex coordinates with a drawing

node-graph/graster-nodes/Cargo.toml

@@ -17,6 +17,7 @@ default = ["std"]
 shader-nodes = [
 	"std",
 	"dep:graphene-raster-nodes-shaders",
+	"dep:wgpu-executor",
 ]
 std = [
 	"dep:graphene-core",
@@ -39,6 +40,7 @@ node-macro = { workspace = true }
 # Local std dependencies
 dyn-any = { workspace = true, optional = true }
 graphene-core = { workspace = true, optional = true }
+wgpu-executor = { workspace = true, optional = true }
 graphene-raster-nodes-shaders = { path = "./shaders", optional = true }
 
 # Workspace dependencies