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/Model/User/CookieTest.php

@@ -35,7 +35,7 @@ class CookieTest extends MockedTest
 	/** @var MockInterface|BaseURL */
 	private $baseUrl;
 
-	protected function setUp()
+	protected function setUp(): void
 	{
 		StaticCookie::clearStatic();
 
@@ -45,7 +45,7 @@ class CookieTest extends MockedTest
 		$this->baseUrl = \Mockery::mock(BaseURL::class);
 	}
 
-	protected function tearDown()
+	protected function tearDown(): void
 	{
 		StaticCookie::clearStatic();