ENH: Snapshot Check / Step

[tangkong]

Expected Behavior

There have been a few requests for a snapshot step. Take a list of PV's/devices/components and record their values. This would be a step that always passes, and simply outputs information in a table in the report.

This dovetails into a request for comparing snapshots between checkouts, but that would be a bigger lift (need to store results in some machine readable format, specify one in the checkout, print the diff). I'm not entirely sure we should support this, but I'd argue it gets left out of the first pass here.

Current Behavior

Behavior does not exist

Possible Solution

Is most simply a passive step, but would be useful as an active step as well.

Context

Requests from Nick / Lasers&Timing

Your Environment

pcds-5.8.0, atef 1.2.0