* Remove unit from garmin connect
* Remove unit from hvv departures
* Remove device class timestamp from device condition and trigger
* Remove unit from systemmonitor
* Use device class constant for timestamp in ring
* added device classes for electrical measurement
(cherry picked from commit 2409fe19ed43bef568a0cca826652867d3a2d71a)
* upadte power factor unit (%)
* update power factor unit (%)
* Add above and below to sensor condition extra_fields
* Change unit_of_measurement to suffix in extra_fields
* Check if sensor has unit when getting capabilities
* Improve tests