CircusPython_BLE: update for CircuitPython 5.0.0-beta.0

[dhalbert]

First redone Learn Guide code for new BLE API. Program structure somewhat simplified.

@tannewt adding you in case you have general BLE-use style suggestions. We might think about some helper functions (like making advertising simpler).

Tested on my CircusPython rig with current Bluefruit app.

[dhalbert]

I think the most obvious helper function would be to add start_advertising() to Service.

from adafruit_ble import BLERadio
from adafruit_ble.advertising.standard import ProvideServicesAdvertisement
from adafruit_ble.services.nordic import UARTService

ble = BLERadio()
uart_service = UARTService()
advertisement = ProvideServicesAdvertisement(uart_service)

ble.start_advertising(advertisement)

Reduce that to:

from adafruit_ble import BLERadio
from adafruit_ble.services.nordic import UARTService

ble = BLERadio()
uart_service = UARTService()

uart_service.start_advertising(ble)    # or ble.start_advertising(uart_service)

One less import, and one less line of code.

[tannewt]

Updated example looks good!

My preference would be to leave the advertising as is rather than add a helper. Adding a helper blurs the two phases of BLE. The first is advertising and the second is service-oriented. It is a little longer but I think it is clearer.