[Feature Request][Facet mosaic] Add a way to write/read the profile to/from the X5 DSK

[PaulZC]

See this forum post for details.

We should add #559 at the same time. The user could then move the file from unit to unit over USB; no SD swaps required!

[PaulZC]

Note to self:

Instead of using the DSK to do the transfer, we could use daisy-chaining - if the user has two units connected using a DATA port or RADIO port cross-over cable.

On the donor, create a daisy-chain from (e.g.) COM4 (ESP32 pins 25 and 4) to COM3 (DATA connector).
Echo the profile through COM4->COM3 using the same eecm (exeEchoMessage) commands.
On the recipient, create the same daisy-chain.
Wait for ASCII to arrive via COM3->COM4.
Strip the GPS Week / TOW, and write each line to the profile file in flash.

No SD shenanigans needed!