Adding new recipes for Encore, Stimulus & AssetMapper (#1202)

* Adding new recipes for Encore, Stimulus & AssetMapper

* StimulusBundle 1.0 -> 2.9

* updating namespace

* moving encore recipe changes to 2.0

* conflict with older version of flex

* adding ux_controller_link_tags() to recipe

* adding documentation to importmap

* updating message to match core

* Adding ux translator

* fixing translations path

* Documenting the new add-lines configurator

* Fixing translator initial version

* shorten to just var

* remove ux alias - there is no one package to install UX packages currently

* fixing wrong package name

symfony/stimulus-bundle/2.9/assets/controllers/hello_controller.js

@@ -0,0 +1,16 @@
+import { Controller } from '@hotwired/stimulus';
+
+/*
+ * This is an example Stimulus controller!
+ *
+ * Any element with a data-controller="hello" attribute will cause
+ * this controller to be executed. The name "hello" comes from the filename:
+ * hello_controller.js -> "hello"
+ *
+ * Delete this file or adapt it for your use!
+ */
+export default class extends Controller {
+    connect() {
+        this.element.textContent = 'Hello Stimulus! Edit me in assets/controllers/hello_controller.js';
+    }
+}