Investigate alternatives to sir-trevor

[corylown]

[cbeer]

Just noting some prior work + research: https://github.com/projectblacklight/spotlight/pull/2193

https://github.com/Automattic/isolated-block-editor (stand-alone Gutenberg) is probably a very strong contender if it's truly been disconnected from wordpress/php. https://github.com/codex-team/editor.js was probably the strongest contender in 2019, and probably worth another look.