Get bridged AP interface name from Wifi HAL.

In bridged AP VTS test, need to get the interface name from bridged AP
from Wifi HAL.
As Wifi HAL is still in HIDL interface, need to use HIDL API to obtain
the bridged AP interface name.

Test: atest VtsHalHostapdTargetTest
Bug: 211073349
Change-Id: Ib594877899ff0fe3ef0a7f01fdb169204dff6a74