Implement status byte

[biemster]

The FindMy protocol adds a status byte in the advertisement, and for example the project https://github.com/dakhnod/FakeTag is using this. The https://github.com/biemster/FindMy/ report requester is now parsing this, so it would be nice to have the ability to send it as well.

[olivluca]

FakeTag uses 2 bits to encode battery status and the remaining 6 is a counter of the detections (I suppose that since he's just interested in seeing if there is new mail, on the receiving end he just checks that the counter has changed, so it doesn't matter if he doesn't get a timely report).
I think that here you could simply use the status byte for the battery status in %.
Or do the same as FakeTag and register the key presses, so you could use the st17h66 exactly like FakeTag.
Your call.

[biemster]

After key cycling I'm going to work on this (it's a lot easier to work on this now, now GCC can compile the thing!)