Add RSSI threshold

[rVlad93]

I've just installed this integration today after becoming aware that I can enable bluetooth tracking on my Everything Presence Lite. Because this is the only tracker I have deployed around the house I can't use it as a room presence as is. The tracking won't change because the device is still seen, even at -92db RSSI. Distance has been reduced to 5m but that didn't change. Is there a way to implement an option to mark the device as not_home when the RRSI is below a certain threshold or when the distance exceeds the set value?