Add ::IDENTITY to node macro to return a ProtoNodeIdentifier that is always a &'static str (#2842)

* fix warnings on master

* make the `ProtoNodeIdentifier` of a Node be accessible and always a borrowed `&'static str`

* always generate `node_name::identifier()`, even with `skip_impl`

* make `FrontendNodeType` use Cow

* remove broken `DocumentNodeDefinition`s for old GPU nodes

* don't reexport `graphic_element` in it's entirety, only data structures

* adjust everything to use the new `node_name::identifier()`

* fixup imports for wasm

* turn identifier fn into a constant

editor/src/messages/tool/tool_messages/artboard_tool.rs

@@ -567,7 +567,7 @@ mod test_artboard {
 			Ok(instrumented) => instrumented,
 			Err(e) => panic!("Failed to evaluate graph: {}", e),
 		};
-		instrumented.grab_all_input::<graphene_std::append_artboard::ArtboardInput>(&editor.runtime).collect()
+		instrumented.grab_all_input::<graphene_std::graphic_element::append_artboard::ArtboardInput>(&editor.runtime).collect()
 	}
 
 	#[tokio::test]