Add a new "Voice input & output" top-level section of system settings.

Add a new "Voice input & output" top-level section of system settings.
This replaces the existing "Text-to-speech" section, placing that
inside, along with a link to the newly exposed voice search settings
(which will soon be expanded) and a link to the LatinIME settings
(pending a link to a new section in LatinIME for just voice settings,
including the comma setting and a new input language setting).

The VoiceSearch and LatinIME links are smart enough to remove themselves
if those don't exist on the device.