Create common database accessors

All database access should go through pfs_utils ics_utils. This includes:

• opdb
• qadb
• star_catalog (gaiadb)

Users and libraries that access the database should standardize on this access.

This ticket is for creating a generic DB access class, mostly by moving/copying the existing interfaces (e.g. from spt_operational_database and spt_qa_database, etc). This access class will include features from other tickets contained within the parent epic (e.g. using context managers, providing pandas convenience methods, etc).

Specific follow-up tickets will be created for converting existing code to the new interface once it's done. This should include appropriate deprecation warnings and a timed release to allow users to update local code.

Edit: this will not deal with the items in the spt_ repos but will focus only on adding accessors to the ics_utils (*not pfs_utils) for now.