Fix Sequel deprication warnings
Fix Sequel deprication warnings

Sequel throws deprication warnings when using its older symbol qualifying syntax (`table__column`).
Additionally, `Model.table_name` in `sequel` can return a non-`String` value.

Uses `::Sequel.qualify` to join `table_name` and `column`.
Uses the `Sequel::SQL::QualifiedIdentifier` returned from `Chewy::Type::Adapter::Sequel#full_column_name` appropriately in the relevant `scope` filters.

toptal/chewy,DNNX/chewy,petalmd/chewy