Preprocess super group implementation for dark dets

We need the ability to run a higher level preprocessing pipeline on specific groups (wafers, bands, etc) before the main pipelines in order to make use of dark detectors for analysis. These are only found in the 90 GHz band so they would not be loaded when preprocessing is divided by wafer and band. This would use the same config file but have its own section which decides on what detectors to load and have a separate list of processes. This could be saved into a different manifest db and h5 file if required, though we don't expect to put any heavy functions in there. It would then be wrapped into aman with different axes and used in the respective functions. Any outputs would not be saved into proc_aman or the main manifest dbs.

The issue names no files or tests; start by tracing the existing preprocessing pipeline and how aman, proc_aman, and the manifest databases are integrated. Done would mean a separate configurable group-level preprocessing stage for selected detectors, with its own process list and axes, while keeping its outputs out of proc_aman and the main manifests.