TSL: NodeKeywords - Cleanup (#28476)

Looks like `NodeKeywords.nodes` is used more as an object than as an array since it's accessed with a `name` which I assume is a `string`.

examples/jsm/nodes/core/NodeKeywords.js

@@ -3,7 +3,7 @@ class NodeKeywords {
 	constructor() {
 
 		this.keywords = [];
-		this.nodes = [];
+		this.nodes = {};
 		this.keywordsCallback = {};
 
 	}