Add config entry for Flu Near You (#32858)

* Add config flow for Flu Near You

* Cleanup

* Cleanup

* Add tests

* Add test requirements

* Code review

* Reduce unnecessary async-ness

* Handle API registration

* Cleanup

* Update homeassistant/components/flunearyou/.translations/en.json

Co-Authored-By: Paulus Schoutsen <paulus@home-assistant.io>

* Code review

* Ensure config schema allows additional keys

Co-authored-by: Paulus Schoutsen <paulus@home-assistant.io>