Dashboard fixes

• enable PythonAlgorithm module
• remove PARAVIEW_ENABLE_MATPLOTLIB flag. now the related modules are built when Python is enabled.
• fix numpy/matplotlib-based tests. none of them were getting enabled due to missing Python executable needed to check by find_python_module
• fix #18801 (closed). paraview-modules.json and vtk-modules.json is now generated in the build directory to help debugging.
• move several internal python modules to paraview.detail package
• update several Python algorithms to use Python C API instead of runstring API.
• improve vtkMultiProcessControllerHelper::ReduceToAll to use collectives instead of point-2-point communication
• misc testing related fixes.