binder: Implement network addition/removal

Implement the |IIface.AddNetwork| & |IIface.RemoveNetwork| binder calls.
Also hookup the network addition notifications to BinderManager for
creating corresponding network binder objects. The network binder
objects are keyed using |ifname|_|network_id|.

BUG: 30015382
Change-Id: I0842563e74ff8b120d34f63fa28965bf264bb55f
TEST: Ran the integration tests under |wificond|.
Signed-off-by: Roshan Pius <rpius@google.com>
10 files changed