Aligned sensostar mqtt discovery to updated underlying sensostar driver

[ovettel]

• Replaced current_status field with status (which is the one provided by the underlying sensostar driver)
• Removed meter_timestamp, since it's (currently) not provided by the underlying driver (and probably overhead, anyways)

Both changes will fix warning messages when new telegrams arrive and get parsed my mqtt

[weetmuts]

Thanks! Please join this conversation: wmbusmeters/wmbusmeters#927

My hope is that we can automate the generation of the mqtt discovery messages.
New drivers are written in xmq see drivers/src (xml which can also be converted in to json).

The --metershell=....
is invoked when the first telegram arrives and the shellscript gets METER_DRIVER which is the generic source for the meter and the actual decoded content METER_JSON which also includes back references into the meter driver.

With this we should be able to compose a complete mqtt discovery message.