rework most of the rest of the entity multimethods

src/metabase/db.clj

src/metabase/models/card.clj

src/metabase/models/card_favorite.clj

src/metabase/models/dashboard.clj

src/metabase/models/dashboard_card.clj

src/metabase/models/dashboard_subscription.clj

src/metabase/models/database.clj

src/metabase/models/field.clj

src/metabase/models/field_values.clj

src/metabase/models/foreign_key.clj

src/metabase/models/interface.clj

src/metabase/models/query_execution.clj

src/metabase/models/session.clj

src/metabase/models/setting.clj

src/metabase/models/table.clj

src/metabase/models/user.clj