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>

esphome/config_validation.py

@@ -1556,3 +1556,17 @@ def polling_component_schema(default_update_interval):
             ): update_interval,
         }
     )
+
+
+def url(value):
+    import urllib.parse
+
+    value = string_strict(value)
+    try:
+        parsed = urllib.parse.urlparse(value)
+    except ValueError as e:
+        raise Invalid("Not a valid URL") from e
+
+    if not parsed.scheme or not parsed.netloc:
+        raise Invalid("Expected a URL scheme and host")
+    return parsed.geturl()