Enhanced Bluetooth HFP support in ModemManager & PulseAudio

Control your phone calls from Bluetooth HFP devices such as headsets or car multimedia systems! I implemented a lot of features of the [Bluetooth HFP 1.8 specification](https://www.bluetooth.com/specifications/specs/hands-free-profile-1-8/) and tested it in [postmarketOS](https://postmarketos.org), such as: - Dialing numbers. - Accepting a call. - Rejecting a call. - Hanging up a call. - Send DTMF tones during a call to navigate phone menus. - Report service, roaming, battery, signal status to the Bluetooth HFP device. - Enhanced error reporting to provide the Bluetooth HFP device more information why an error is returned such as: no network service, operation not allowed, etc. - Enhanced calling line reporting provides the Bluetooth HFP device the number of an incoming call which can be displayed on the device. Merge request is already made upstream at PulseAudio: https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/693 Currently, under review and not ready to be sh