Add config flow to iCloud (#28968)

* iCloud: setup ConfigFlow and prepare for more platforms

- add config flow + tests
- fix existing services
- add play_sound & display_message services
- document services
- can use devices with the same name
- prepare to add sensor platform

* Review : not copy account conf

* Review: Safer test patch

* Review: remove reset_account

* Review: Use executor_job while IO

* Review: Use executor_job while IO 2

* Review: use hass.helpers.storage.Store()

* Review: no IO in tests

* Remove reset from services.yaml

* Review: remove authenticate.return_value = Mock()

* Review: do not initialize the api with the mocked service

* isort

* Review: @MartinHjelmare Test config flow with all steps

* Review: Fix failed tests names

* Codevov: Add one missing test