Add support for exposing node parameter inputs (#866)

* Add exposing inputs to graph

* Use uuids and better node positioning

* Fix accidentally refering to the wrong grid spacing

* Secondary input without primary input

* Cleanup document node types

* Rename to input and addend

frontend/src/wasm-communication/messages.ts

@@ -82,6 +82,8 @@ export class FrontendNode {
 
 	readonly displayName!: string;
 
+	readonly primaryInput!: FrontendGraphDataType | undefined;
+
 	readonly exposedInputs!: NodeGraphInput[];
 
 	readonly outputs!: FrontendGraphDataType[];