ORUR01Handler should load an encounter's location from the database

When submitting a Xform, the visit_id related with the patient and the encounter is not being updated. In the encounter table, the visit_id value is being filled with NULL.

This is after configuring visits with the ExistingVisitAssignmentHandler.
ORUR01Handler creates a new location which it assigns the correct existing locationId. But since this location is not loaded from the database, it is assigned a uuid different from that in the database. So when the handler tries compare the visit location with that of the encounter using the equals operator which uses the uuid field, they are considered as different locations and hence the encounter is not assigned to the visit.