Show default property values in widget configuration forms

The widget type configuration can define default values for widget properties.
When these properties are referenced by the configuration layout, these properties should be shown (but not persisted when not changed).

Properties that are not referenced should not be initialized (otherwise they'll appear as custom properties, and this is confusing for the end user).

Mechanism to retrieve default values is partially implemented (to check) but anyway default values retrieval was buggy on 5.9.3 so this requires an upgrade of the layout-api and layout-io dependencies (see NXP-15360)