modules: nanopb: introduce new module

Add the nanopb library and generator tools as a module.
Nanopb is a small code-size Protocol Buffers implementation in ansi C.
It is especially suitable for use in microcontrollers,
but fits any memory restricted system.

Nanopb home: https://jpa.kapsi.fi/nanopb/



Signed-off-by: Pieter De Gendt <pieter.degendt@basalte.be>