Fix tests

- Fix InstallerTest case
- Fix native function mocking
- Add returntype for Unit-Tests
- Fixing ExtendedPDO test troubles
- Fix wrong class inheritance path for DatabaseTestTrait.php
- Fix SyslogLogger Server Exception for PHP8
- Add user/contact to database.fixture.php
- Avoid invalid rollbacks for test setup in PHP8

tests/src/Core/Cache/CacheTest.php

@@ -81,7 +81,7 @@ abstract class CacheTest extends MockedTest
 
 	abstract protected function getInstance();
 
-	protected function setUp()
+	protected function setUp(): void
 	{
 		parent::setUp();