editoria11y v1 plugin is no longer working; remove since updated wagtail includes accessibility checking

[rlskoeser]

Here's John Jameson's write-up about editoria11y v2
https://editoria11y.princeton.edu/2023/03/towards-v2/

And here is the documentation for setup https://itmaybejj.github.io/editoria11y/

It looks like the path and configuration have changed; probably not too difficult to update.

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update: newer versions of wagtail include accessibility checking built on axe tools, so we can just remove editoria11y

[rlskoeser]

editora11y v1 removed in #414