add support of environtment variable for tab & group

packages/node_modules/@node-red/runtime/lib/flows/Flow.js

@@ -396,6 +396,17 @@ class Flow {
         return undefined;
     }
 
+
+    /**
+     * Get a group node instance
+     * @param  {String} id
+     * @return {Node}   group node
+     */
+    getGroupNode(id) {
+        const groups = this.global.groups;
+        return groups[id];
+    }
+
     /**
      * Get all of the nodes instantiated within this flow
      * @return {[type]} [description]
@@ -404,6 +415,57 @@ class Flow {
         return this.activeNodes;
     }
 
+    /**
+     * Get a flow setting value deined in this flow. 
+     * @param  {String} key
+     * @return {Object} result containinig val property or null
+     */
+    getFlowSetting(name) {
+        const flow = this.flow; 
+        if (flow.env) {
+            if (!name.startsWith("$parent.")) {
+                if (!flow._env) {
+                    const envs = flow.env;
+                    const entries = envs.map((env) => [env.name, env]);
+                    flow._env = Object.fromEntries(entries);
+                }
+                const env = flow._env[name];
+                if (env) {
+                    let value = env.value;
+                    const type = env.type;
+                    if ((type !== "env") || (value !== name)) {
+                        if (type === "env") {
+                            value = value.replace(new RegExp("\\${"+name+"}","g"),"${$parent."+name+"}");
+                        }
+                        try {
+                            if (type === "bool") {
+                                const val = ((value === "true") ||
+                                             (value === true));
+                                return {
+                                    val: val
+                                };
+                            }
+                            if (type === "cred") {
+                                return {
+                                    val: value
+                                };
+                            }
+                            var val = redUtil.evaluateNodeProperty(value, type, null, null, null);
+                            return {
+                                val: val
+                            };
+                        }
+                        catch (e) {
+                            this.error(e);
+                            return null;
+                        }
+                    }
+                }
+            }
+        }
+        return null;
+    }
+
     /**
      * Get a flow setting value. This currently automatically defers to the parent
      * flow which, as defined in ./index.js returns `process.env[key]`.
@@ -412,6 +474,10 @@ class Flow {
      * @return {[type]}     [description]
      */
     getSetting(key) {
+        const result = this.getFlowSetting(key);
+        if (result) {
+            return result.val;
+        }
         return this.parent.getSetting(key);
     }