allow switching user displayed in calendar (#3314)

src/Form/CalendarForm.php

@@ -0,0 +1,34 @@
+<?php
+
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Form;
+
+use App\Form\Type\UserType;
+use Symfony\Component\Form\AbstractType;
+use Symfony\Component\Form\FormBuilderInterface;
+use Symfony\Component\OptionsResolver\OptionsResolver;
+
+class CalendarForm extends AbstractType
+{
+    public function buildForm(FormBuilderInterface $builder, array $options): void
+    {
+        $builder->add('user', UserType::class, [
+            'required' => false,
+            'attr' => ['onchange' => 'this.form.submit()']
+        ]);
+    }
+
+    public function configureOptions(OptionsResolver $resolver): void
+    {
+        $resolver->setDefaults([
+            'csrf_protection' => false,
+            'method' => 'GET',
+        ]);
+    }
+}