Implement node graph gpu execution via vulkano and rust gpu (#870)

* Add Executor abstraction

* Resolve inputs for proto nodes by adding compose nodes

* Add infrastructure for compiling gpu code

* Integrate nodegraph gpu execution into graph-crafter

* Extract graphene core path from env vars

* Make Color struct usable for gpu code

.gitignore

@@ -1,3 +1,4 @@
 target/
 *.spv
 *.exrc
+rust-toolchain