Fix delegation to _apply_{action type}_action() methods

This change is needed for "UpdateRawPropertyAction" to be translated
to "_apply_update_raw_property_action" correctly.
Change _validate_object_properties() to take property names

Prior to this, the method took property objects, however, if we want
to reuse the method for raw property actions, we'll have to stick to
names as there are no Property objects stored in the classes
UpdateRawPropertyAction and UnsetRawPropertyAction.
Catching/report missing property names in raw property actions
WIP: Implement applying of update-raw-property actions

What's missing here is an implementation of _update_raw_property(),
as called in _apply_raw_property_action(). And tests.
WIP: Add incomplete scenario tests for update-raw-property actions