[ADD] web: overflow-visible utility class

Define "Bootstrap v5 ready" utility-class to handle the property
overflow: visible.
This class definition can be safely removed after migrating to v5.

task-2742831

Part-of: odoo/odoo#83403

addons/web/static/src/libs/bs5_utility_classes.scss

@@ -76,3 +76,11 @@ $position-properties: (
   }
 }
 
+// == Overflow: visible
+//------------------------------------------------------------------------------
+// "Bootstrap v5 ready" utility-class to handle the property overflow: visible.
+// This class definition can be safely removed after migrating to BTS v5.
+
+.overflow-visible {
+  overflow: visible !important;
+}