Prepare for 0.12.0 release

[hakonanes]

Description of the change

Prepare for the 0.12.0 release by bringing all changes since last release to the main branch.

I set the release date in the changelog two days from now, to Saturday April 13.

Progress of the PR

As per the release guide:

• [x] Ensure that all tutorial notebooks run fine (at least on macOS)
• [x] Update contributor list order according to the number of line additions on GitHub
• [x] Set version to 0.12.0 in orix/__init__.py and changelog.

I'd also like to

• [x] bring in #486

For reviewers

• [x] 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.
• [ ] Contributor(s) are listed correctly in __credits__ in orix/__init__.py and in .zenodo.json.

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[hakonanes]

The only un-reviewed changes are in the last two commits:

• 305c29e
• 6ee9982

[hakonanes]

I plan to bring in #486 this evening and then release.

[hakonanes]

Thanks! I rebased. Will merge and release once checks pass.