[Cover] Started implementing Cover plugin: base class, route, base templates, added tabs in profile template

plugins/Cover/Controller/Cover.php

@@ -0,0 +1,42 @@
+<?php
+
+// {{{ License
+
+// This file is part of GNU social - https://www.gnu.org/software/social
+//
+// GNU social is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// GNU social is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with GNU social.  If not, see <http://www.gnu.org/licenses/>.
+
+// }}}
+
+namespace Plugin\Cover\Controller;
+
+use App\Core\Form;
+use function App\Core\I18n\_m;
+use Symfony\Component\Form\Extension\Core\Type\FileType;
+use Symfony\Component\Form\Extension\Core\Type\HiddenType;
+use Symfony\Component\Form\Extension\Core\Type\SubmitType;
+use Symfony\Component\HttpFoundation\Request;
+
+class Cover
+{
+    public function cover(Request $request)
+    {
+        $form = Form::create([
+            ['cover', FileType::class,   ['label' => _m('Cover'), 'help' => _m('You can upload your personal cover. The maximum file size is 2MB.')]],
+            ['hidden', HiddenType::class, []],
+            ['save',   SubmitType::class, ['label' => _m('Submit')]],
+        ]);
+        return ['_template' => 'Cover/cover.html.twig', 'form' => $form->createView()];
+    }
+}