Shaders: graster-nodes no-std fixups (#2984)

* wgpu-executor: remove useless features

* wgpu-executor: cleanup copy-pasted code

* gcore-shaders: no_std fixups

node-graph/gcore-shaders/src/lib.rs

@@ -1,3 +1,5 @@
+#![cfg_attr(not(feature = "std"), no_std)]
+
 pub mod blending;
 pub mod choice_type;
 pub mod color;