pybricks/bluetooth: Add bt classic inquiry scans.

[jaguilar]

Any Pybricks device running btstack can now issue Bluetooth classic inquiry scans to find and report discoverable devices.

This API is experimental and we can change it later if we don't like it. But it's nice because it can be used to concretely demonstrate that the EV3's BTStack layer is doing something! This also should give some indication of the structure by which we'll add further classic functionality (more functions and switch entries in bluetooth_btstack_classic.c). If it's preferred to have it in the same file as the LE code, we can, but this structure is scarcely more expensive and a little more neatly organized.

You can test it with this program:

from pybricks.tools import run_task
from pybricks.experimental.btc import scan


async def do_scan():
    print("Start bluetooth scan...")
    devices = await scan()
    print("Scan complete, devices found: ")
    for device in devices:
        print(device)


run_task(do_scan())

[github-actions]

Download the artifacts for this pull request:

• pr_number.zip
• mpy-cross.zip
• movehub-firmware-build-4581-git4638309d.zip
• ev3-firmware-build-4581-git4638309d.zip
• technichub-firmware-build-4581-git4638309d.zip
• nxt-firmware-build-4581-git4638309d.zip
• cityhub-firmware-build-4581-git4638309d.zip
• primehub-firmware-build-4581-git4638309d.zip
• essentialhub-firmware-build-4581-git4638309d.zip
• buildhat-firmware-build-4581-git4638309d.zip

[coveralls]

coverage: 50.566% (+0.02%) from 50.55%
when pulling ebf3c1e on jaguilar:ev3-bluetooth-scan
into fcfdf4e on pybricks:master.

[jaguilar]

Rebased this commit atop all the other refactoring work that has happened recently to btstack, and verified that everything is still working.