Support Battery Level Status BLE characteristic

[liamcharger]

I would like the Battery Level Status characteristic to be implemented (see 3.29 in this spec)

I'm working on some features in InfiniLink that require the charging state to be known.

At the same time, this may allow InfiniTime to show itself in the iOS battery widget, like it is shown here:

[Ralimbahere]

I would love to have that!

[liamcharger]

As it turns out, the battery characteristic is enough for iOS to display the device in the widget, but the connection needs to be encrypted. (When using ANCS, it appeared.)

[cyberneel]

@liamcharger Is it possible for the icon to be some watch?

[liamcharger]

In theory, the icon should be a watch when the GAP Appearance value is set to Generic Watch (0xC0). The value is set here. According to the doc, the value is currently being set for a generic mouse, which is incorrect, but when I switched it to 0xC0, it didn't change.