Upcoming CODAL WebUSB comms might require a memory layout change

[microbit-carlos]

There is some upcoming CODAL work to create a comms system to exchange data between the micro:bit and the online editors via WebUSB:

• Design sidechannel comms approach we're happy to live with for some time (mailbox) lancaster-university/codal-microbit-v2#271
• Implement system for data log to be read over webUSB lancaster-university/codal-microbit-v2#270

This won't have any impact to the MicroPython user API, but if an approach that reserves some RAM to exchange data is selected, it could require some memory layout changes in this project as well.

This is not yet implemented in CODAL v0.2.50 (hopefully it will be in the next tag), so this ticket at the moment is mostly to schedule the work for a future integration.