Use prosemirror-editor

[rhystmills]

Co-authored with @samanthagottlieb

What does this change?

This PR replaces Scribe editors in tagmanager with a ProseMirror editor provided by the prosemirror-editor package, created for this purpose.

We're replacing Scribe because it's deprecated and introduces vulnerabilities into our projects.

The new editor also introduces hover and disabled states for the buttons, plus additional disabled styles when the entire editor is disabled.

Before	After

How to test

1. Run this project locally according to the instructions in the readme or deploy to CODE (CODE probably will be be less painful).
2. Edit an existing contributor tag to see the rich text editor use for the Description/Profile field. Try the formatting options.
3. Save the tag. Are your changes persisted on refresh?
4. If you're feeling thorough: open the network tab and clear the requests. Edit the tag's rich text, and save the changes. A POST request should go to the url similar to https://tagmanager.local.dev-gutools.co.uk/api/tag/12345. Does the description sent in that request look valid? Is the bold text serialised as <b> tags and the italic text as <i> tags? (It should). Are new paragraphs serialised as new <p> tags? (They should).
5. Try removing your tag edit CODE permissions. Wait a minute or two and see if they apply (the editor should be disabled if you see a warning that you don't have tag edit permissions)

[davidfurey]

• 1. Tested in CODE
• 2. Edit an existing contributor tag to see the rich text editor use for the Description/Profile field. Try the formatting options.
• 3. Save the tag. Are your changes persisted on refresh?
• 4. If you're feeling thorough: open the network tab and clear the requests. Edit the tag's rich text, and save the changes. A POST request should go to the url similar to https://tagmanager.local.dev-gutools.co.uk/api/tag/12345. Does the description sent in that request look valid? Is the bold text serialised as <b> tags and the italic text as <i> tags? (It should). Are new paragraphs serialised as new <p> tags? (They should).
• 5. Try removing your tag edit CODE permissions. Wait a minute or two and see if they apply (the editor should be disabled if you see a warning that you don't have tag edit permissions)