[WIP] OpenPMD frontend update

[henrynjones]

This work-in-progress PR replaces the now defunct Pull request #4848 (thank you @neutrinoceros ) and addresses issue #4757 by using the backend-agnostic openPMD-api as the IO module instead of the previous h5py.

TODO

• Add sorted particles to the particle grid in which they are located, for the short term this will only work for ADIOS2, file-based iteration encoded datasets with the particlePatches.

  • For HDF5 files, record_component.available_chunks() only contains one chunk and all levels cover the entire domain. We might have to trim/mask higher level data so that only level 0 data exists on the entire domain, and each subsequent level covers only the refined region.

• Still haven't looked at string handing for file path patterns. Would be great to load a dataset series from file-based iteration-encoded diagnostics. Right now yt uses [0-9] or dd???/dd??? or diag_name_??? while openpmd-api uses %T or %06T for example.

• More information to come in the next few days. For now I have attached a notebook demonstrating some improvements and outstanding issues here: https://github.com/henrynjones/yt_supplemental/blob/main/PR_update.ipynb

• This is a messy version full of comments and print statements for debugging. I mostly wanted to get my branch back up to speed.

PR Checklist

• New features are documented, with docstrings and narrative docs
  • Modern mesh refinement tools similar to the boxlib frontend for ADIOS2 files.
  • More to add here
• Adds a test for any bugs fixed. Adds tests for new features.