Revise visit grouping scheme for cosmicray

The need to specify groups of visits in the registry is a burden when trying to reduce data as it's coming off the telescope, and the current scheme is inflexible since it doesn't allow different groupings.
A new feature (DM-49300, added slightly after LSST 29 was branched, but may be backported) may allow us to essentially define the visit groups within the pipeline rather than beforehand in the registry. The defining of visit groups could also be configurable, allowing multiple modes of operating, e.g.:
1. One visit per group (as for the observing.yaml pipeline currently).
2. Automatic grouping of visits using some algorithm (as done by defineVisitGroups.py currently).
3. Manually specified groups (via a configuration parameter).
4. Lookup visit_group in registry?

There are multiple steps to achieving this:
1. Upgrading to an LSST release that contains this feature (earliest version w_2025_12).
2. Modifying the feature to suit our needs (e.g., we may need access to the registry, add ability to move outputs around).
3. Convert the PFS code to use the new feature.