[PnCCD] Use new APIs to store & retrieve calibration constants
Description
We want to consolidate access to CalCat on the extra.calibration API. This is part of that. In particular, it moves the constant injection away from iCalibrationDB and calDBRemote.
How Has This Been Tested?
Running notebooks interactively. I'll also run CI (expecting the dark constants produced to be in a new format).
Checklist:
- My code follows the code style of this project.