dev: Add mage target for serve dev webui tool

DEVELOPMENT.md

@@ -360,10 +360,10 @@ The development server runs on `http://localhost:8080` and will proxy all API ca
 
 #### Interactive development stack launcher tool
 
-In order to easily launch development environments in different deployment contexts, this script configures and starts a development environment for The Things Stack, allowing users to choose between local and staging environments, enable branding, and configure cloud-hosted mock setups. You can launch it via:
+In order to easily launch development environments in different deployment contexts, this mage target configures and starts a development environment for The Things Stack, allowing users to choose between local and staging environments, enable branding, and configure cloud-hosted mock setups. You can launch it via:
 
 ```bash
-$ node tools/js/serve-dev-stack.js
+$ tools/bin/mage dev:serveDevWebui
 ```
 
 It will interactively guide you through the desired setup and launches the The Things Stack Enterprise as well as a frontend development server wia webpack.

tools/js/serve-dev-stack.js → tools/js/serve-dev-webui.js

@@ -136,9 +136,6 @@ if (relevantSetEnvs.length > 0) {
       }
       envConfig += stagingConfig
     }
-  } else {
-    // Cypress setup
-    envConfig = baseConfig + localConfig
   }
 
   const envVars = envConfig

tools/mage/dev.go

@@ -349,6 +349,13 @@ func (Dev) StartDevStack() error {
 	return execGo(logFile, logFile, "run", "./cmd/ttn-lw-stack", "start", "--log.format=json")
 }
 
+func (Dev) ServeDevWebui() error {
+	if mg.Verbose() {
+		fmt.Println("Starting the webui with interactive configs")
+	}
+  return sh.RunV("node", "tools/js/serve-dev-webui.js")
+}
+
 func init() {
 	initDeps = append(initDeps, Dev.Certificates, Dev.InitDeviceRepo)
 }