Pympdata

- redesign vector-field halo-filling code enabling separate code for normal and parallel logic (thanks Delcior)
- extended docstrings and test coverage for boundary conditions (periodic, extrapolated)

- redesign of halo-filling architecture enabling exchanges of domain slabs instead of per-grid-cell logic (kudos Delcior)

- update links in README to reflect GitHub org move to open-atmos
- fix JSON syntax in .zenodo.json and add a CI workflow for checking it

- added an option to `Stepper::__init__` to select halo-filling traversal order (left first or right first) + major code refactor around halo-filling logic (kudos piotrbartman!)

- added `.zenodo.json` file with metadata for Zenodo releases
- improved Numba error messages through closure function renaming, adding source file names to namedtuple types and avoiding cryptic magick in method-name construction within Field::assemble
- fixed Numba compilation issue with shared advector (by introducing `lru_cache` for `make_indexers`)
- README updates

thanks Delcior for help

- final JOSS paper edits
- pre-commit hooks setup (incl. CI checks)
- CI steps (main build jobs depend now on codecov, pylint and precommit)
- added `-We` to `pytest` call in codecov workflow
- tokens for ghapi & pypi-publish version bump in CI scripts