Add distributed contourtree
Note: This merge request replaces !2267 (closed) due to build bot failures.
This merge requests integrates work on distributed parallel merge tree computation into vtk-m. To improve scaling, we add e new ContourTreeUniformDistributed filter that computes a distributed representation of the contour tree and will serve as basis for feature-based analysis in the the ECP ALPINE project.
Edited by Gunther Weber