`ls` should show `pre.load` objects, with appropriate statuses for new vs ref

[brodieG]

This is going to be a PITA to implement, so we're deferring for now. See the docs for the pre.load param for unitize for more details.

[brodieG]

Possible implementation would be to compute hash and store those so we don't have to store the entire object, but can still tell when the objects are not the same as when the tests were run originally. Unfortunately, there does not seem to be built in hashing so we may need to rely on digest or some such.

Most likely place to store this would be just above the utils environment so if we wanted to we could let updateLs stop at that environment as the last environment, and record the contents, though in reality we should only need to do this once per unitizer so more likely we'll precompute this elsewhere and have updateLs look it up.