unmock all test doubles after each test

[Chemaclass]

📚 Description

Currently, you can mock a particular function with custom logic, but there is no way to rollback the mock for other tests. The goal is to be able to rollback the mocked behaviour to the original one.

🔖 Changes

• Add new asserts assert_is_mock, assert_is_not_mock
• Call clear_mocks after run_tear_down for each test

✅ To-do list

• [x] I updated the CHANGELOG.md to reflect the new feature or fix
• [x] I updated the documentation to reflect the changes