fine grained reactivity:
existing key in source changes --> only observer having read the key are notified
add/delete key in source changes --> all source observers are notified
Co-authored-by: Aaron Bohy <aab@odoo.com>
Co-authored-by: Géry Debongnie <ged@odoo.com>
Co-authored-by: Mathieu Duckerts-Antoine <dam@odoo.com>