Add support for ADIOS2

[eschnett]

Conduit supports currently only ADIOS 1, and the latest ADIOS 1 release happened 7 years ago. Please add support for ADIOS2.

As context: The Einstein Toolkit collaboration https://einsteintoolkit.org is looking for a widely-supported metadata standard for structured grids with both adapative mesh refinement and multi-patch systems. In particular, we're looking for a standard that is already supported by visualization tools such as VisIt.

It is important for us that we can perform efficient I/O on HPC systems. We've had problems with HDF5 in the past, and ADIOS2 seems to be a library with many of the same features as HDF5 but which is much more focussed on performance.

I don't want to promise anything, but we might also consider contributing towards ADIOS2 support in Conduit.

[BenWibking]

I wanted to chime in to say that this would also be extremely useful for our codes, especially for writing extracts from Ascent.

[cyrush]

I would love for this to exist and we can collaborate on this.

We have Fides (a mesh data model on top of ADIOS2) support in Ascent, however generic Conduit to ADIOS2 would open up many more use cases and more performant I/O.

[eschnett]

I've created a working branch for ADIOS2 support: #1389

[JustinPrivitera]

Fantastic!