Shaders: add gcore-shaders and make graster-nodes no-std (#2925)

* gcore-shaders: add crate, move `color` and `blending` from gcore

* gcore-shaders: move `AsU32`

* gcore-shaders: move `ChoiceType`, switch `Cow` for `&str`, adjust node macro

* gcore-shaders: move `registry::types`

* gcore-shaders: move `context::Ctx`

* raster-nodes: make it `no_std` with `std` feature

* gcore-shaders: fix doctest

node-graph/gcore/src/value.rs

@@ -120,7 +120,6 @@ impl<'i, T: Clone + 'i> Node<'i, ()> for DebugClonedNode<T> {
 	type Output = T;
 	#[inline(always)]
 	fn eval(&'i self, _input: ()) -> Self::Output {
-		#[cfg(not(target_arch = "spirv"))]
 		// KEEP THIS `debug!()` - It acts as the output for the debug node itself
 		log::debug!("DebugClonedNode::eval");