Refactor the interface between paraview and smtk resources

This commit introduces vtkSMTKResource, a server-side pipeline source that represents an SMTK resource. It also appends pqSMTKBehavior to construct a vtkSMTKResource when the pipeline source for a resource is queried but cannot be found. As a result, any operation that results in the construction of a new resource will now trigger the rendering of the resource (in addition to the paraview-style readers and resource creation actions).