Proposal: Test yaml for each component (#5398)

* Test for each component.

* When possible use commandline substitution.

* Add wildcard support.

* end file with new line.

* Move component tests into subfolder.

* Add component test to pipeline.

* Remove trailing whitespace.

* add restore python step.

* Add `. venv/bin/activate` to pipeline.

* step `changed-components` needs `common` step.

* start `list-components-changed.py` different.

* iterate on pipeline stage `list-components`.

* Update `checkout` action.

* Rename test folder from `tests` to `_test`.

* validate file exists.

* Move component test folder.

* extend list-components to include child components.

* File does not end with a newline

* Handle empty list-components matrix.

* list-components also check for changes in tests folder.

* Improve `list-components.py`.

* `*` is a forbidden character for filenames on windows.

---------

Co-authored-by: Your Name <you@example.com>
Co-authored-by: Keith Burzinski <kbx81x@gmail.com>

tests/components/adc/test.esp8266.yaml

@@ -0,0 +1,4 @@
+sensor:
+  - platform: adc
+    id: my_sensor
+    pin: VCC