Changes to metadata extraction and VisitInfo creation

Yesterday I merged DM-15914 which introduces a new package named astro_metadata_translator as a unified interface for extracting standardized information from file headers. Previously the code for extracting Butler information and the code for calculating an afw VisitInfo were distinct. Unifying the two is an important prerequisite for Butler Gen3 ingest to work.

obs_subaru has been updated to use the new system and obs_decam and obs_cfht will follow shortly. All obs packages should use the new scheme if they are to support Butler Gen3.

As part of this work I did discover that the telescope location for Blanco and the air pressure at Subaru were being calculated incorrectly.

Please let me know if you see any unexpected warnings when reading in HSC files. I have initially turned off pedantic header translation (where bad headers cause errors and instead issue warnings) but we can evolve how this works with experience.