improve tests for nodeDir

Adds new resources (loose files, non NR pkgs, NR modules, NR Plugins)
Adds new tests
#getNodeFiles - new tests below
  √ Finds nodes and icons only in nodesDir with files, icons and valid node-red packages
  √ Should not find node-red node in nodesDir with files, icons and valid node-red packages
  √ Should not find node-red node in nodesDir when regular package and valid node-red packages
#getModuleFiles - new tests below
  √ gets a nodes module files
  √ Finds only 1 node-red node in nodesDir amongst legacy nodes and regular nodes
  √ Finds a node-red node in nodesDir with a sub dir containing valid node-red package
  √ Finds 2 node-red node and 1 plugin in nodesDir (in root of dir)
  √ Finds 2 node-red node and 1 plugin in nodesDir pointing to a node_modules dir

test/unit/@node-red/registry/lib/resources/nodesDir1/node-red-node-testnode/icons/test.svg

@@ -0,0 +1 @@
+<svg width="40" height="60" viewBox="0, 0, 40, 60" xmlns="http://www.w3.org/2000/svg"><path d="M30.999 31.005v-3h-6.762s.812-12.397 1.162-14 .597-3.35 2.628-3.103 1.971 3.103 1.971 3.103l4.862-.016s-.783-3.984-2.783-5.984-7.946-1.7-9.633.03c-1.687 1.73-2.302 5.065-2.597 6.422-.588 4.5-.854 9.027-1.248 13.547h-8.6v3H18.1s-.812 12.398-1.162 14-.597 3.35-2.628 3.103-1.972-3.102-1.972-3.102l-4.862.015s.783 3.985 2.783 5.985c2 2 7.946 1.699 9.634-.031 1.687-1.73 2.302-5.065 2.597-6.422.587-4.5.854-9.027 1.248-13.547z" fill="#fff"/></svg>

test/unit/@node-red/registry/lib/resources/nodesDir1/node-red-node-testnode/main.js

@@ -0,0 +1,4 @@
+
+    (function() {
+        console.log("hello from regular module main.js")
+    })()

test/unit/@node-red/registry/lib/resources/nodesDir1/node-red-node-testnode/package.json

@@ -0,0 +1,19 @@
+{
+  "name": "node-red-node-testnode",
+  "version": "1.0.0",
+  "description": "A node-red node that does nothing other than exist",
+  "main": "main.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [
+    "node-red"
+  ],
+  "node-red": {
+    "nodes": {
+      "testnode": "index.js"
+    }
+  },
+  "author": "@testyMcTersterson",
+  "license": "MIT"
+}