WifiManager: add iface name and mode labels

Connectivity service needs to get the interface name and intended ip
configuration mode for softap.
This CL adds the interface name and softap target mode variables to
use to insert the extra info into the wifi ap state change broadcast.

Note: additional CLs are needed to verify the iface name and mode.  The
mode tracking is still in progress.

Bug: 62076211
Test: frameworks/base/wifi/tests/runtests.sh
Test: frameworks/opt/net/wifi/tests/wifitests/runtests.sh
Test: manually verified the name in the broadcast
Change-Id: I64e1d13a9e422945fe9c4c268c206da365d0a3eb