Added basic network request handling

Supported basic network request handling, attach/detach
from data network. Also supported dynamic priority update
based on config changed event.

Bug: 196597630
Test: Manual
Merged-In: I0b3e8d5c511b5b76d38b81a9c28956cf4aee3961
Change-Id: I0b3e8d5c511b5b76d38b81a9c28956cf4aee3961