Removed dependance upon corgi::kMaxComponentCount.
Removed dependance upon corgi::kMaxComponentCount.

SceneLab used to require the kMaxComponentCount constant from
the entity system.  Since that has been removed, this change
makes it instead use the current number of registered components.

Change-Id: I0e1d53fe04b1165888dbdc759150de57cfdbca1d

google/scene_lab,google/scene_lab