Add option to not randomize initial avatar orientation (which we do at present), the default behavior is unchanged.
Add option to not randomize initial avatar orientation (which we do at present), the default behavior is unchanged.

PiperOrigin-RevId: 455601410
Change-Id: Ib46a7560ff52a27d00e4a57da2e5daf87f3b34a5

deepmind/meltingpot,deepmind/meltingpot