feat(lexical): add lexical to admin

[andrewleith]

Summary | Résumé

This is an experiment to try using the Lexical editor inside of admin. It would replace our manual text areas that we require users to enter markdown into.

Right now I just plunked it on the /welcome page while I was trying to get it working.

Lessons learned:

• Don't use the vanilla js version, since no one does so its very hard to find information

Next steps:

• Figure out how to make it spit out its content as markdown
• Use it on the templates page
• Review form's implementation and use that in place of this stock version

Screenshot

[github-actions[bot]]

:test_tube: Review environment

https://st6mwjuohbg5xodge5azl4mieq0snblr.lambda-url.ca-central-1.on.aws/