Compound Filters

[mechelon]

docs / description: tbc

[what-the-diff]

• Added a new filter bag class to allow for compound filters.
• Changed the signature of Database::filterBy() to accept either a single Filter or an instance of FilterBag (breaking change).
• Fixed some type hints and docblocks in various places, including adding missing ones where necessary.
• Removed namespaces
• Replaced all tests with it() blocks
• Added dataProvider for limit test (limit 1 and 2)
• Moved Http::fake to the top of each test block, so that we can use them in multiple assertions within a single it block without having to repeat ourselves too much or have duplicate code between different tests/assertions
• Added a test for the FilterBag class
• Refactored all tests to use it() instead of @test and removed TestCase inheritance