Implement external custom components installing from YAML (#1630)

* Move components import loading to importlib MetaPathFinder and importlib.resources

* Add external_components component

* Fix

* Fix

* fix cv.url return

* fix validate shorthand git

* implement git refresh

* Use finders from sys.path_hooks instead of looking for __init__.py

* use github:// schema

* error handling

* add test

* fix handling git output

* revert file check handling

* fix test

* allow full component path be specified for local

* fix test

* fix path handling

* lint

Co-authored-by: Guillermo Ruffino <glm.net@gmail.com>

tests/test4.yaml

@@ -160,3 +160,9 @@ display:
     lambda: |-
       it.rectangle(0, 0, it.get_width(), it.get_height());
 
+external_components:
+  - source: github://esphome/esphome@dev
+    refresh: 1d
+    components: ["bh1750"]
+  - source: ../esphome/components
+    components: ["sntp"]