MFC r342945, r342947, r343020

Add bluetooth-config script to simplify setting up bluetooth connections to
devices like mice, keyboards, bt-audio, ...

This script currently allows scanning for nearby devices, adds one to
/etc/bluetooth/hosts, adds an entry to hcsecd's conf and if it is a HID, add an
entry to bthidd's configs, as well.

Submitted by: erdgeist <erdgeist at erdgeist.org>
Approved by: bapt
MFC after: 2 weeks
Differential Revision: D3778
Reviewers: bapt, emax