Improve sensor battery readings

[adamdewey]

Describe the bug Several reports from multiple sources that the sensor battery readings are unreliable - e.g. often jumping from 50 to 48 to 52, even down to 28.

Could we perhaps improve the accuracy by taking an average of, say, the last 20 battery readings (rounded to the nearest integer)

To Reproduce Steps to reproduce the behavior:

1. Set up a BM sensor with CCA
2. Watch the battery reading...

Expected behavior Battery reading to be reasonably accurate so that users know when to replace it.

Smartphone (please complete the following information):

• Device: Samsung Galaxy Tab A8
• OS: Android 13
• Version V 0.5.3

Additional context Add any other context about the problem here.

[adamdewey]

@louisaw123 can testify more I'm sure

[adamdewey]

Wait, there's already a ticket that Louisa created - will close this in favour of that