Extend the nanopb sample with a Kconfig option to optionally include
a field in a protobuf message.
Signed-off-by: Pieter De Gendt <pieter.degendt@basalte.be>
The latest version of nanopb allows for using kconfig symbols in files
with an "options.in" extension.
Signed-off-by: Pieter De Gendt <pieter.degendt@basalte.be>