consolidate initialize and run into async api

a container is now either allocated, and ephemeral, or initialized +
about to run. if initialization fails, the container is marked
'completed' and 'failed'.

still a work-in-progress, but functional. (for example the giant
goroutine in RunContainer will be cleaned up.)

[#79618102]

Signed-off-by: Michael Fraenkel <fraenkel@us.ibm.com>
stop passing ports to registry.Create

...now that garden is the source of truth

Signed-off-by: Michael Fraenkel <fraenkel@us.ibm.com>