Adds V3 API samples for cells and multinic

Adds V3 API samples for cells and multinic extensions.
Bundling them together to save on review load

Partially implements blueprint v3-api-unittests
Partially implements blueprint v3-api-specification

Change-Id: I50840b3d900fbc8ff4f655e4188cc886d7065729
Merge "Adds V3 API samples for cells and multinic"