Switch phpunit assertion arguments

[Tomas Norkūnas]

PHPUnit expects first argument to be the expected data and the second one as actual but I found in most tests where I did look that they are switched and the expected data is provided as a second argument

[Bruno Casali]

I'll reopen it since the issue was not entirely fixed.

There are still some places where it should be updated, like in the asserSame usages e.g.:

• $this->assertSame($response['type'], 'documentAdditionOrUpdate'); at tests/Endpoints/IndexTest.php lines 205, 244 and more.