Fix issue #22860466: viapi security bug - rubber stamping in nested VIs

The settings activities that get launched directly by voice now
protect themselves to only execute if they were actually directly
launched by the voice interaction service, rather than allowing
any activity currently under voice control to abuse them.

Note the original code also allowed them to execute regardless of
whether they were running under voice, since it allowed for a null
saved state.  I assume that was a mistake, so have removed it.

Change-Id: Ib2269a7ee13016d300afba7fa257bfaca8990fab