Compatibility with CircuitPython

[llamafilm]

This is a no-op for anyone using pack_advertisement.

I could not find any way to use that function with adafruit_ble in CircuitPython, so I made pack_service_data public and changed its format for compatibility. That library has its own class to create Advertisements, which adds the AD type, length, and name.

Example usage:

from adafruit_ble import BLERadio
from adafruit_ble.advertising import Advertisement
from bthome import BTHome

beacon = BTHome(debug=True)
beacon.temperature = 25
bthome_service_data = beacon.pack_service_data(BTHome.TEMPERATURE_SINT16_X100)
bthome_advert = Advertisement()
bthome_advert.data_dict[0x16] = bthome_service_data

ble = BLERadio()
ble.name = "Feather Sense"
ble.start_advertising(bthome_advert)