fix loading node package in nodesDir on linux

fixes #3861

packages/node_modules/@node-red/registry/lib/localfilesystem.js

@@ -156,6 +156,16 @@ function scanDirForNodesModules(dir,moduleName,package) {
                 }
             }
         }
+
+        // if we have found a package.json, this IS a node_module, lets see if it is a node-red node
+        if (!isNodeRedModule && files.indexOf('package.json') > -1) {
+            package = getPackageDetails(dir) // get package details
+            if(package && package.isNodeRedModule) {
+                isNodeRedModule = true
+                files = ['package.json'] // shortcut the file scan
+            }
+        }
+
         for (let i=0;i<files.length;i++) {
             let fn = files[i];
             if (!isNodeRedModule && /^@/.test(fn)) {