Explore expanding predeployment to non-external/sync start games

[sei-bstein]

We don't currently permit predeployment of gamespaces for games which are not external + sync-start. Being able to do this will improve our ability to predict/manage load on the game engine cloud provider (e.g. VMWare).

Definitely a separate lift, but we'll need to consider #408 as we do this - modularizing logic will be relevant to both.