Frontend (#4232)

* Initial implementation of backend for frontend.

* Frontend fixes (#4205)

* Send data to frontend api withoud baseTopic preffix

* Send frontend api requests to mqtt

* Fix topic name sanitisation

* Fix base_topic trimming

* Update frontend.js

* Add zigbee2mqtt-frontend dependency

Co-authored-by: Koen Kanters <koenkanters94@gmail.com>

* Dont' setup separate MQTT connection.

* Correctly stop

* Add frontend tests.

* [WIP] Bindings structure change (#4233)

* Change bindings location

* Bump frontend version

* Republish devices on bindings change

* Fix data structure

* Fix  payload double encoding

* Change endpoints structure

* Expose config to bridge/info

* Fix typo

* Updates

Co-authored-by: Koen Kanters <koenkanters94@gmail.com>

* Resend states on ws reconnect

* Update deps

* Bump frontend (#4264)

Co-authored-by: John Doe <nurikk@users.noreply.github.com>

lib/controller.js

@@ -13,6 +13,7 @@ const path = require('path');
 const assert = require('assert');
 
 // Extensions
+const ExtensionFrontend = require('./extension/frontend');
 const ExtensionPublish = require('./extension/publish');
 const ExtensionReceive = require('./extension/receive');
 const ExtensionNetworkMap = require('./extension/networkMap');
@@ -67,6 +68,10 @@ class Controller {
             this.extensions.push(new ExtensionBridge(...args, this.enableDisableExtension));
         }
 
+        if (settings.get().experimental.frontend) {
+            this.extensions.push(new ExtensionFrontend(...args));
+        }
+
         if (settings.get().advanced.legacy_api) {
             this.extensions.push(new ExtensionBridgeLegacy(...args));
         }
@@ -143,6 +148,7 @@ class Controller {
         // MQTT
         this.mqtt.on('message', this.onMQTTMessage.bind(this));
         await this.mqtt.connect();
+        this.mqtt.publish('bridge/state', 'online', {retain: true, qos: 0});
 
         // Send all cached states.
         if (settings.get().advanced.cache_state_send_on_startup && settings.get().advanced.cache_state) {