Throw SecurityException in sendVisualVoicemailSms()

Previously if the caller is not the active VVM service, the exception
will be consumed by the Binder because it is a oneway method.

This CL changes the method to non-oneway so the caller will receive
the exception. Docs are also updated.

Change-Id: Iedf96539be3958a92e151b926ee069d6edfc4d09
Fixes: 35854031
Test: CTS - VisualVoicemailServiceTest
2 files changed