Add a module which is responsible for getting offset between RTCs
used for system clock on NET and APP cores. After getting an offset
between NET and APP clocks, it can be used for logging timestamping
on NET core to ensure that timestamping is in sync on both cores.
Synchronization is done using PPI, IPM task and events and RTC
capture feature.
Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>
