[D11] frontend/bootstrap integration WIP. Discovered some hidden dependencies. Generate slightly faster bootstrap if you don't want the intro sequence (only saves a couple of seconds at the moment though since it's working quite well in "parallel" with the splash screens), fix some issues where code wasn't yielding enough to give good parallelism between loading and frontend. Gets into the FE pretty quickly now on a package build, but the warmup continues behind the scenes so will need to check Bootstrap.completed at some point before trying to connect to a server, hopefully the player won't be quick enough, plus other work should further reduce the warmup bundle size.