Remove the Hallo Editor - now provided as an external package

[lb-]

• Removal of the Wagtail Hallo editor, adds notes to the release notes
• Resolves Remove support for Hallo editor #6228
• New external package (alpha) is available via https://pypi.org/project/wagtail-hallo/0.1.0a1/
• Please review the removals carefully, the goal is to remove Hallo only but keep some of the core utils such as whitelister & editorhtml intact (some may be removed in the future but not in scope of this work)

How to test this

• Check out this branch locally
• Important: Delete the built static assets at wagtail/admin/static and then run the Wagtail build pipeline nvm use then npm run build - this is required so that validation can be done without the styles/JS provided by Wagtail and only the ones provided by the new package.
• Then install the package as per the documentation (to also test these instructions make sense), remember to update your bakerydemo (or other local Wagtail instance) settings to use the hallo editor
• You may need to make a new page that uses the hallo editor, here are two example models.

[squash-labs]

Manage this branch in Squash

Test this branch here: https://lb-featurehallo-editor-removal-fp9zn.squash.io

[thibaudcolas]

@lb- looks like it’s all passing :) I won’t be able to review this this week but should be able to help from next week onwards.

[lb-]

@thibaudcolas ready for a review now
cc @zerolab

[lb-]

rebased on main & fixed up the conflicts with the black formatter change

[lb-]

Reminder to self - rebase needed

[thibaudcolas]

Looking excellent @lb-. I’ve picked up very minor things. I think they’re worth fixing but should be very straightforward and this will be good to merge afterwards. This is as thorough of a cleanup as I’ve ever seen!

I have yet to try the wagtail-hallo package, will get to it next, considering the feedback on #6228 I think we can merge this already and if anything further comes up we can pick it up in wagtail-hallo.

[lb-]

@thibaudcolas thanks, I did my best to get the draftail.js to be consistently Draftail as part of this - some comments have been moved to pydoc style module descriptions instead as that seemed more appropriate.

Can you take another look please, I am happy to merge in but just wanted to get another pass.

Thanks heaps

[thibaudcolas]