adding all get all channel functions in channel repo

packages/Webkul/Core/src/Repositories/ChannelRepository.php

@@ -100,4 +100,16 @@ class ChannelRepository extends Repository
             $channel->save();
         }
     }
+
+    public function getAllChannel() {
+        $data = $this->model->get()->toArray();
+
+        $channel = [];
+
+        foreach($data as $key => $value) {
+            $channel[$value['id']] = $value['code'];
+        }
+
+        return $channel;
+    }
 }