Guides View VDB Action regression exceptions

* DesignerProperties
 * NoSuchElement Exception occurs if no VDB is found in the workspace by
   the VdbResourceCollectorVisitor.
 * Due to use of Collections.unModifiableCollection wrapper
 * Handle with test for isEmpty

* VdbReousrceCollectorVisitor
 * Incorrect return logic for visit() method. Should always return true
   in order for project and folder members to be tested.
 * Better utilise the resource filter which is already being utilised but
   only testing it the resource is a file.