Need a "Test as Remembered" flag

[denised]

As we start to do things like update allocations, we need the ability to keep the deep Excel tests running --- which means we need the ability to set the test environment to be what was in place when the expected.zip was created. In practical terms, for land models, this might mean using a different cohort than the "current" one.

Not totally sure how much of an issue this is yet, but wanted to get this written down so we don't forget.

[denised]

Unassigning myself since this is going on pause.