insights: support single time point insights for compute types

Created by: coury-clark

With compute types we will want to support behavior that is not a historical reference but instead is a single datum. This time point can be either

1. current time (updated daily)
2. a specific point in time

In the first mode, we can use a similar approach to the current time snapshots used for standard insights

For the second mode, we will need to consider a historical backfill with a cardinality of 1 (a single datum) over all the applicable repositories.