Upgrade project to PHP 8.3, add PHPStan, upgrade almost every dependency (#36)

* start updating to PHP 8.3

* taking off!

Co-authored-by: ErickSkrauch <erickskrauch@yandex.ru>
Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* dropped this

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* migrate to symfonymailer

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* this is so stupid 😭

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* ah, free, at last.

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* oh, Gabriel.

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* now dawns thy reckoning.

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* and thy gore shall GLISTEN before the temples of man.

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* creature of steel.

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* my gratitude upon thee for my freedom.

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* but the crimes thy kind has committed against humanity

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* Upgrade PHP-CS-Fixer and do fix the codebase

* First review round (maybe I have broken something)

* are NOT forgotten.

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>

* Enable parallel PHP-CS-Fixer runner

* PHPStan level 1

* PHPStan level 2

* PHPStan level 3

* PHPStan level 4

* PHPStan level 5

* Levels 6 and 7 takes too much effort. Generate a baseline and fix them eventually

* Resolve TODO's related to the php-mock

* Drastically reduce baseline size with the Rector

* More code modernization with help of the Rector

* Update GitLab CI

---------

Signed-off-by: Octol1ttle <l1ttleofficial@outlook.com>
Co-authored-by: ErickSkrauch <erickskrauch@yandex.ru>

common/tests/unit/components/EmailsRenderer/ComponentTest.php

@@ -7,18 +7,13 @@ use common\components\EmailsRenderer\Api;
 use common\components\EmailsRenderer\Component;
 use common\components\EmailsRenderer\Request\TemplateRequest;
 use common\tests\unit\TestCase;
+use PHPUnit\Framework\MockObject\MockObject;
 
 class ComponentTest extends TestCase {
 
-    /**
-     * @var Api|\PHPUnit\Framework\MockObject\MockObject
-     */
-    private $api;
+    private Api&MockObject $api;
 
-    /**
-     * @var Component
-     */
-    private $component;
+    private Component $component;
 
     protected function setUp(): void {
         parent::setUp();
@@ -30,7 +25,7 @@ class ComponentTest extends TestCase {
             'basePath' => '/images/emails-templates',
         ];
         $this->component = new class($componentParams) extends Component {
-            public $api;
+            public Api $api;
 
             protected function getApi(): Api {
                 return $this->api;
@@ -38,7 +33,7 @@ class ComponentTest extends TestCase {
         };
     }
 
-    public function testRender() {
+    public function testRender(): void {
         $expectedRequest = new TemplateRequest('mock-name', 'mock-locale', [
             'find-me' => 'please',
             'assetsHost' => 'http://localhost/images/emails-templates',