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>

.php-cs-fixer.dist.php

@@ -0,0 +1,28 @@
+<?php
+declare(strict_types=1);
+
+/**
+ * Do not adjust this file for your environment manually.
+ * Copy it as .php-cs-fixer.php (without .dist part) and then adjust.
+ */
+
+$finder = PhpCsFixer\Finder::create()
+    ->in(__DIR__)
+    ->exclude('data')
+    ->exclude('docker')
+    ->exclude('frontend')
+    ->notPath('common/emails/views')
+    ->notPath('common/mail/layouts')
+    ->notPath('#.*/runtime#')
+    ->notPath('autocompletion.php')
+    ->exclude('_output')
+    ->exclude('_generated')
+    // Remove the line below if your host OS is Windows, because it'll try to fix file, that should be executed
+    // on Linux environment
+    ->name('yii');
+
+return Ely\CS\Config::create([
+    'self_accessor' => false,
+])
+    ->setParallelConfig(PhpCsFixer\Runner\Parallel\ParallelConfigFactory::detect())
+    ->setFinder($finder);