improve Status performance; add ability to retrieve latest N migrations

[mfridman]

Currently the implementation of the status command is to loop over all the migrations and get the db metadata one-by-one. I think we can do better by retrieving all migrations at once, although to future proof we could just paginate which would be a few round trips.

This would enable us to list latest N migrations, which has been requested in #254

Lastly, this will enable us to display migrations based on their applied order, instead of their migration file order. See comment #280 (comment). This is important because in #262 we added out-of-order migrations, so the file order no longer is the source of truth.