Block editor support

[jonathanstegall]

• Co-Authors Plus admin picker
• Co-Authors Plus front end display
• CMB2 field groups
• Publish preview URL for posts
• WP Category Permalink support (ideally this forum post will help us know what to do)
• ArcAds DFP ACM Provider support
• Data project HTML support
• Inline images, captions, credits
• Test all the CMB2 fields
• Pasting text from browser, Word, Google Docs, etc