Added a new simulated board, which models the NRF52832 SOC.
Its main use is for workstation testing and simulation of
the BLE stack and any application which relies mostly on it.
It uses BabbleSim (http://Babblesim.github.io) for the radio
simulation.
And the NRF52 HW models hosted in that same GitHub organization:
https://github.com/BabbleSim/ext_NRF52_hw_models
For speed it uses the POSIX arch to (not) emulate the CPU.
It uses Vanilla Zephyr, with a couple of configuration differences:
* It uses (like other POSIX arch boards) the system libC
* It does not use the nrfx hosted by Zehpyr in ext/, but the one
provided by the HW models.
Otherwise it relies in the same drivers as the real NRF52 boards.
Signed-off-by: Alberto Escolar Piedras <alpi@oticon.com>