Explicitly include <ArborX_DetailsUtils.hpp> from <ArborX.hpp>

[dalg24]

Rational: backward compatibility

Andrey did too good of a job at cleaning up unnecessary header includes and this led to the current situation where <ArborX_DetailsUtils.hpp> is not included in the <ArborX.hpp> header when MPI is not enabled which broke Cabana.

[aprokop]

Good find, didn't realize that. Guess we don't include ArborX_DBSCAN.hpp either.

[aprokop]

@dalg24 I've been playing around with iwyu, and was trying to figure out what files to have in ArborX.hpp:

#ifndef ARBORX_HPP
#define ARBORX_HPP

#include <ArborX_Config.hpp> // IWYU pragma: export

#include <ArborX_AccessTraits.hpp>       // IWYU pragma: export
#include <ArborX_Box.hpp>                // IWYU pragma: export
#include <ArborX_BruteForce.hpp>         // IWYU pragma: export
#include <ArborX_Callbacks.hpp>          // IWYU pragma: export
#include <ArborX_CrsGraphWrapper.hpp>    // IWYU pragma: export
#include <ArborX_Exception.hpp>          // IWYU pragma: export
#include <ArborX_GeometryTraits.hpp>     // IWYU pragma: export
#include <ArborX_HyperBox.hpp>           // IWYU pragma: export
#include <ArborX_HyperPoint.hpp>         // IWYU pragma: export
#include <ArborX_HyperSphere.hpp>        // IWYU pragma: export
#include <ArborX_IndexableGetter.hpp>    // IWYU pragma: export
#include <ArborX_KDOP.hpp>               // IWYU pragma: export
#include <ArborX_LinearBVH.hpp>          // IWYU pragma: export
#include <ArborX_PairValueIndex.hpp>     // IWYU pragma: export
#include <ArborX_Point.hpp>              // IWYU pragma: export
#include <ArborX_Predicates.hpp>         // IWYU pragma: export
#include <ArborX_SpaceFillingCurves.hpp> // IWYU pragma: export
#include <ArborX_Sphere.hpp>             // IWYU pragma: export
#include <ArborX_TraversalPolicy.hpp>    // IWYU pragma: export

#ifdef ARBORX_ENABLE_MPI
#include <ArborX_DistributedTree.hpp> // IWYU pragma: export
#include <ArborX_PairIndexRank.hpp>   // IWYU pragma: export
#endif

#endif

I'm not sure what the rule of thumb is on this kind of thing. Should we include just high level stuff, or transitives too? What do we want users to include on their own? Should it be ArborX_Core.hpp, ArborX_Clustering.hpp, ArborX_Interpolation.hpp?

[dalg24]

Ignoring the HIP failure