[FR]: Changing device_class and unit_of_measurement

[Barma-lej]

Please change device_class to duration and unit_of_measurement to min for sensor.[mower]_rainsensor_delay and sensor.[mower]_rainsensor_remaining according Available device classes

[Barma-lej]

And also change device_class to duration and unit_of_measurement to h for sensor.[mower]_blades_current_on_time, sensor.[mower]_blades_total_on_time, sensor.[mower]_blades_reset_at_hours and sensor.[mower]_total_worktime