Support for Adafruit Feather 2350 HSTX

[mattuna15]

Switch GPIOs used for HSTX to match Adafruit HSTX layout

[MichaelBell]

Thank you for taking the time to make a PR with these updates.

I'd prefer not to just switch one set of magic numbers for another. It's unfortunate that the adafruit_feather_rp2350 board header doesn't have defines for these pins, but would you be able to set some appropriately named defines for the pin numbers at the top of dvhstx.cpp, and switch those on based on whether ADAFRUIT_FEATHER_RP2350 is defined? Then we will have a way of easily extending it for other board types in future.