enhancement: When input sensors are failing - report them in the attributes

[jbruntt]

I just experienced that the sensors for electriciy buy and sell prices had the state "unknown". This caused HSEM to repeatedly log about missing sensors in the hsem.log.
I suggest that when configured sensors are nok OK, HSEM reports this somewhere, including the sensor-names.
It could be in an attribute in the working mode sensor.
This is from the attributes as they are looking when I have the unknown status for the price sensors.

status: error
description: Some of the required input sensors from the config flow is missing or not reporting a state yet. Check your configuration and make sure input sensors are configured correctly.

[woopstar]

I will fix this :) Thank you for the feedback

[woopstar]

Release v3.5.0-beta4 addresses this issue and will be included in 3.5.0, which is scheduled to be released soon.