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/Console/ConfigConsoleTest.php

@@ -38,7 +38,7 @@ class ConfigConsoleTest extends ConsoleTest
 	/** @var IConfig|LegacyMockInterface|MockInterface */
 	private $configMock;
 
-	protected function setUp()
+	protected function setUp() : void
 	{
 		parent::setUp();