Add more VTS tests for SupplicantStaIface

This covers the following APIs by adding tests to
ISupplicantStaIface:
ISupplicantStaIface::setExternalSim(),
ISupplicantStaIface::addExtRadioWork(),
ISupplicantStaIface::removeExtRadioWork()

Bug: 33457575
Test: VTS tests pass
Change-Id: Ie252ecf8e6e0cdc9d669a5fec18e076dc2d03eba
1 file changed