Adapt to iic startExposures finishing quickly

INSTRM-1193 changes the way very long running IIC sequences like startExposures run. Basically, the command finishes once resources have been allocated instead of finishing after all exposures have been taken, in the indeterminate future. You track the progress of the exposure sequence using keywords.

The sunssActor currently pretends it is commanding a new-style sequence, by having the command time out after 5s or so. Update the logic to do it correctly.