Number entity refactoring to support unit conversion
NumberEntity now supports temperature unit conversion following a similar pattern
as the unit conversion supported by SensorEntity.
Temperature conversion will automatically be done for number entities with device
class set to temperature to the temperature unit configured by the user.
To make this possible, custom component integrations should be updated to override
properties native_max_value, native_min_value, native_step,
native_unit_of_measurement, native_value instead of max_value, min_value,
step, unit_of_measurement, value and to override methods async_set_native_value
and set_native_value instead of async_set_value and set_value.
The same renaming has been done for _attr_* attributes as well as members of
NumberEntityDescription.
In Home Assistant Core 2023.1, overriding async_set_value, max_value, min_value,
set_value, step, unit_of_measurement, value, setting _attr_max_value,
_attr_min_value, _attr_unit_of_measurement, _attr_step, _attr_value and
setting max_value, min_value, unit_of_measurement, step on instances of
NumberEntityDescription is no longer supported.