* Add suggested_unit_of_measurement attribute to sensors
* Lazy calculation of initial entity options
* Add type alias for entity options
* Small tweak
* Add tests
* Store suggested_unit_of_measurement in its own option key
* Adapt to renaming of IMPERIAL_SYSTEM
* Fix rebase mistakes
* Apply suggestions from code review
Co-authored-by: epenet <6771947+epenet@users.noreply.github.com>
Co-authored-by: epenet <6771947+epenet@users.noreply.github.com>