Improved code to extract global temporal variables generated by exodus
reader.

* `vtkExodusIIReader` marks global temporal variables specially. This
  helps downstream filters recognize these arrays as such.
* Deprecating `vtkExtractTemporalFieldData`, the filter is very exodus
  specific hence replacing it with
  `vtkExtractExodusGlobalTemporalVariables`.
* `vtkExtractExodusGlobalTemporalVariables` support extract global
   temporal arrays (similar to vtkExtractTemporalFieldData).
   Additionally, it can handle restart files (a concept supported in
   ParaView).  Addresses paraview/paraview#17851

`extractGlobalTemporalVariables` doesn't test for restart files yet
since VTK reader doesn't support restart files. We'll add a test in
ParaView for the same.