Add option to map Spectrum to FN keys in order to reenable NOAA alert feature

[salokinrekced]

Reviving a conversation earlier that resulted in this fork: https://github.com/bogdanbrudiu/uv-k5-firmware-custom

This reenables NOAA alert and allows Spectrum to be added to the FN keys. Please remap the Spectrum keys to allow NOAA to be reenabled and use the F+5 command to access as it is on the stock firmware.

[cgolchert]

When I look at that fork it is giving me the same options as the main. I need to enable NOAA in the makefile in that fork as well. Which sadly fails to build using the Codespace build method just like the main branch.

/usr/lib/gcc/arm-none-eabi/14.1.0/../../../../arm-none-eabi/bin/ld: firmware section .text' will not fit in region FLASH'
/usr/lib/gcc/arm-none-eabi/14.1.0/../../../../arm-none-eabi/bin/ld: region `FLASH' overflowed by 644 bytes
collect2: error: ld returned 1 exit status
make: *** [Makefile:441: firmware] Error 1