Allows Sequel to reuse an ActiveRecord connection

This is an extension for Sequel that allows it to reuse an existing ActiveRecord connection for database interaction. It supports postgresql, mysql2 and sqlite3 adapters.This can be useful if you're using a library that uses Sequel for database interaction (e.g. Rodauth), but you want to avoid creating a separate database connection. Or if you're transitioning from ActiveRecord to Sequel, and want the database connection to be shared.Note that this is a best-effort implementation, so some discrepancies are still possible. That being said, this implementation passes Rodauth's test suite (for all adapters), which has fairly advanced Sequel usage.