gril: Add parcels for radio-settings driver
rilmodem: Add radio-settings driver

This driver adds support for setting the preferred radio technology.

Based on nemomobile implementation:

https://github.com/nemomobile-packages/ofono/tree/master/ofono

The original author of this code is Jussi Kangas
<jussi.kangas@tieto.com>.
build: Compile ril radio-settings module
ril: Create radio-settings interface
unit: Add tests for ril radio-settings parcels