Update tests: 1. automl.py (#1417)

* Add: Dedicated fixtures location

* Add: Typing to conftest

* Fix: More typing

* Move: Dask fixtures to own location

* Move: backend to it's own fixture location

* Move: Automlstub thing to it's own fixture

* Fix: docstring warning in conftest

* Fix: Remove dead code

* Add: Functionality to skip marked `slow` tests

* Add: Fixture for getting datasets

* Update: Tests for automl.py w/ fixtures, cases, mocks

This commit (too much) focues on extending our pytest capabilities to
make things more modular. Notably, making a fixtures and mocks folders
for testing so there is a unified source of mocks and fixture locations.

Split the tests for automl.py into seperate sub files to allow for an
easier time discerning what is being tested where.

Introduces `pytest_cases` to allow for easier future
testing of properties.

Introduces cached automl models to allow for a quicker time testing
attributes while keeping tests seperate and distinct.

This also rearragnes `unittest` import unfortunatly which causes many
files to be touched.

* Doc: Add documentation about our testing to conftest.py

* Doc: Add a bit more on documenting of tests

* Fix: Add pytest-cases to test dependancies

* Fix: Broken tests

* Fix: Failing test

* Fix: Ordering of check in `_includes`

* Remove `_includes` and use sets instead

* Fix: Black

* Update: test workflow knows about `.pytest_cache`

.flake8

@@ -5,6 +5,7 @@ extend-exclude =
     venv
     .venv
     build
+    autosklearn/automl_common
 extend-ignore =
     # No whitespace before ':' in [x : y]
     E203

.github/workflows/pytest.yml

@@ -137,6 +137,8 @@ jobs:
     - name: Check for files left behind by test
       if: ${{ always() }}
       run: |
+        # Deleting `.pytest_chache` as it's used during testing and not deleted
+        rm -rf ".pytest_cache"
         before="${{ steps.status-before.outputs.BEFORE }}"
         after="$(git status --porcelain -b)"
         if [[ "$before" != "$after" ]]; then