Type check all helpers (#25373)

* Type check all helpers, add inline exclusions for work in progress

* Remove unused Script._template_cache

* Add some missing type hints

* Remove unneeded type: ignore

* Type hint fixes

* Mypy assistance tweaks

* Don't look for None in deprecated config "at most once" check

* Avoid None name slugify attempt when generating entity id

* Avoid None state store attempt on entity remove

homeassistant/helpers/entity_platform.py

@@ -9,6 +9,9 @@ from homeassistant.util.async_ import (
 
 from .event import async_track_time_interval, async_call_later
 
+
+# mypy: allow-untyped-defs, no-check-untyped-defs
+
 SLOW_SETUP_WARNING = 10
 SLOW_SETUP_MAX_WAIT = 60
 PLATFORM_NOT_READY_RETRIES = 10