Import in the executor by default for core integrations (#112127)

* Import in the executor by default for core integration

* merge correct branch in

* Group loading of platforms in the import executor

* adjust test

* remove other pr

* Fix async_prepare_setup_platform test

The message changed because the order changed but was not caught before
merge because it required the combination of PRs to change
the error message

* fix

* tweak

* fix

* self review

* review

* fix hue mocking

* Update homeassistant/loader.py

Co-authored-by: Paulus Schoutsen <balloob@gmail.com>

* lint

* Fix async_get_component loading in the executor when the module is already loaded

The sys.modules check was incorrect (only on dev)

* fix

* Avoid multiple executor jobs with concurrent calls to async_get_component

Return a future that can be awaited if the component is
curently being loaded

* adjust

* coverage

* coverage

* concurrent platforms load test

* doc strings

* coverage

---------

Co-authored-by: Paulus Schoutsen <balloob@gmail.com>

tests/test_loader.py

@@ -1033,6 +1033,14 @@ async def test_async_suggest_report_issue(
     )
 
 
+def test_import_executor_default(hass: HomeAssistant) -> None:
+    """Test that import_executor defaults."""
+    custom_comp = mock_integration(hass, MockModule("any_random"), built_in=False)
+    assert custom_comp.import_executor is False
+    built_in_comp = mock_integration(hass, MockModule("other_random"), built_in=True)
+    assert built_in_comp.import_executor is True
+
+
 async def test_config_folder_not_in_path(hass):
     """Test that config folder is not in path."""