clang-tidy: fix `readability-redundant-casting` lints

Accelerators/Vtkm/Core/vtkmlib/vtkmInitializer.cxx

Accelerators/Vtkm/DataModel/vtkmlib/PolyDataConverter.cxx

CMake/vtkTestingRenderingDriver.cmake

Charts/Core/vtkAxis.cxx

Charts/Core/vtkChartXYZ.cxx

Charts/Core/vtkPlot.cxx

Charts/Core/vtkPlotBox.cxx

Charts/Core/vtkPlotParallelCoordinates.cxx

Charts/Core/vtkPlotPoints.cxx

Charts/Core/vtkPlotRangeHandlesItem.cxx

Common/Core/vtkByteSwap.cxx

Common/Core/vtkDataArray.cxx

Common/Core/vtkIndexedImplicitBackend.txx

Common/Core/vtkLookupTable.cxx

Common/Core/vtkMath.cxx

Common/Core/vtkScalarsToColors.h

Common/DataModel/vtkBoundingBox.cxx

Common/DataModel/vtkCellLocator.cxx

Common/DataModel/vtkDataSet.cxx

Common/DataModel/vtkExtractStructuredGridHelper.cxx