High memory usage TUs

I've been seeing OOM situations arise more and more recently of late with VTK-m. This issue aims to document the high-usage memory TUs. Note that I do not have CUDA enabled, and memory usage tends to be higher with its toolchain.

Configuration: RelWithDebInfo, no CUDA, GCC 10.2.1. Running the build with systemd-run --user -p MemoryMax=$memory --setenv=CCACHE_DISABLE=1 --same-dir --pty ninja -j1 $target

TUs that fail with memory=4G:

• ThirdParty/vtkm/vtkvtkm/vtk-m/vtkm/filter/CMakeFiles/vtkm_filter_contour.dir/ContourInteger.cxx.o
• ThirdParty/vtkm/vtkvtkm/vtk-m/vtkm/filter/CMakeFiles/vtkm_filter_contour.dir/ContourScalar.cxx.o
• ThirdParty/vtkm/vtkvtkm/vtk-m/vtkm/filter/CMakeFiles/vtkm_filter_extra.dir/ClipWithField.cxx.o

TUs that fail with memory=6G:

• N/A

Will update as things progress.

Cc: @vbolea @robertmaynard