Add H5OINA reader and restructure h5ebsd readers

[hakonanes]

Description of the change

• Add minimal H5OINA reader (Oxford h5ebsd format)
• Separate h5ebsd plugin into four plugins for the four h5ebsd formats of kikuchipy (reader/writer), EDAX, Bruker Nano and Oxford Instruments (H5OINA)
• Change the metadata structure returned from all EBSD readers
• Remove deprecated ebsd_metadata() and metadat_nodes()
• Remove deprecated EBSD methods set_experimental_parameters() and set_phase_parameters()

Closes: #141, #466, and #559.

Progress of the PR

• Docstrings for all functions
• Unit tests with pytest for all lines
• Clean code style by running black via pre-commit
• Test H5OINA reader with a dummy dataset
• Remove custom metadata nodes
• Remove EBSD methods set_experimental_parameters() and set_phase_parameters()
• Remove references to deprecations in docs, and generally update them following these changes
• Add H5OINA plugin to list in docs
• Update changelog with added h5ebsd plugin, changed h5ebsd plugins, removed functions and methods, and changed metadata structure (returned from most EBSD readers)

For reviewers

• The PR title is short, concise, and will make sense 1 year later.
• New functions are imported in corresponding __init__.py.
• New features, API changes, and deprecations are mentioned in the unreleased
  section in CHANGELOG.rst.
• New contributors are added to release.py and .all-contributorsrc and the table
  is regenerated.

[hakonanes]

@IMBalENce, I'm done with the H5OINA reader for now and intend to merge this after checks pass so that people can start to use it. If you find the reader cannot read some of your data, we can fix this at some later point.