Create parent task/script for bootstrapping Gen3 repos

Building on recent work to enable bootstrapping the Gen3 ci_hsc dataset with minimal reliance on gen2convert (DM-19614, DM-19615, DM-19622, DM-19531, DM-19272) and improvements to gen2convert itself (DM-18023), write a task/script that can be used to similarly bootstrap other Gen3 repos, starting with RC2.

Steps will include:

• register instrument(s)
• add curated calibrations, via Instrument.writeCuratedCalibrations
• register skymaps(s)
• ingest raws, via RawIngestTask
• add Gen2-calib-repo calibrations, refcats, and BrightObjectMasks via explicit, lower-level calls to gen2convert code in daf_butler.

I do not currently plan to include actually creating the empty repository, which will save this task from having to somehow read in and apply overrides to butler yaml configuration.