ip_utils: add GetDeviceName signal

Add signal to retrieve the device name on platforms where it must be
acquired client-side.

createRingDevice now gets the device name from getDeviceName, which
uses the GetDeviceName signal on Android, iOS, and UWP builds, and
otherwise getHostname for the GNU/Linux, win32, and MacOSX builds.

Change-Id: I81013afdd5d51f3cbd518dca22a4cfdc03f94c59