Enable a BLE workflow

[tannewt]

nRF CircuitPython boards will now provide the file transfer
service defined here: https://github.com/adafruit/Adafruit_CircuitPython_BLE_File_Transfer

USB capable boards will only advertise if previously bonded to a
device or if the reset button is pressed during the fast blue
flashes on start up. When pressed, the board will restart again but
the blue period will not flash.

Boards without USB will always advertise.

When previously bonded, the advertisement is private so that no
other peers can connect. If advertising publicly, the tx power is
lowered to reduce the likelihood of bonding from a distance.

This PR also fixes issues with loading identities of bonded peers
so that our address can now be resolved and we can resolve others'
addresses when scanning.

[dhalbert]

Looks good! I did not test it (I don't have the apps).

I think it would be nice in the long run to factor out the file transfer protocol code in shared/bluetooth.c into its own library (repo?) or at least its own file.

[tannewt]

Looks good! I did not test it (I don't have the apps).

I think it would be nice in the long run to factor out the file transfer protocol code in shared/bluetooth.c into its own library (repo?) or at least its own file.

I just started on adding BLE serial support and I'm making a bluetooth subfolder similar to the usb one. I don't think it should be a separate repo because its build on top of common_hal APIs.