Nanostack eventloop tick timer can be used in case high resolution
platform timer is not needed. One usecase for that is Pelion
Cloud client when using for example cellular connectivity. This enables
PDMC application to enter deep sleep state.
Nanostack related files moved under 'feature/nanostack'
Common libraries moved to 'features/frameworks'
Allow FEATURE_COMMON_PAL still to be defined in the build so
that we don't break any builds.