Add ability to disable BLE workflow

[tannewt]

Call supervisor.disable_ble_workflow() and the BLE workflow will
be disabled until the chip is reset.

This also includes a couple fixes:

1. Terminals can now be deinit by setting the tilegrid to NULL. This
   prevents using the tilegrid before display is init.
2. Fix BLE serial send amount when sending more than a single packet.

Fixes #5049

[tannewt]

@jepler I fixed the build so please take a look.

[jepler]

Thanks, and thanks for some quick answers in discord about the change. No problems spotted, but no testing performed.

[ThomasAtBBTF]

This feature does exactly what I was asking for in #5049
Thank you!
I now can call supervisor.disable_ble_workflow() in boot.py and no "strange" devices are appearing anymore after powering on the board.
As soon as the code in for my Bluetooth HID device is ready in code.py the correct advertising starts.

Remains the question: Is one of the initial devices providing the ability for "over-the-air" updates and if so, can the original workflow be reenabled by CiruitPython code?

[tannewt]

BLE provides functionality via services. A device can advertise different services at different times and provide different services at different times. Advertising only influences when something chooses to connect to another device. It doesn't limit what services are available once a connection is established.

If you want the BLE workflow stuff, then leave it enabled. The advertisements the core does shouldn't prevent HID from working because the HID advertisement will replace the first one.