✨ feat(shortcodes): add `inline` option to image shortcodes

[welpo]

Summary

Adds an inline option to all image shortcodes (except the full_width one, for obvious reasons). When set to true, the image(s) will be displayed inline with the text. The images will be vertically aligned with the text.

Related issue

Idea from #314.

Accessibility

No changes; tested with VoiceOver.

Type of change

• [ ] Bug fix (fixes an issue without altering functionality)
• [X] New feature (adds non-breaking functionality)
• [ ] Breaking change (alters existing functionality)
• [ ] UI/UX improvement (enhances user interface without altering functionality)
• [ ] Refactor (improves code quality without altering functionality)
• [ ] Documentation update
• [ ] Other (please describe below)

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Checklist

• [x] I have verified the accessibility of my changes
• [X] I have tested all possible scenarios for this change
• [ ] I have updated theme.toml with a sane default for the feature
• [X] I have made corresponding changes to the documentation (shortcodes post).