Major UI change - Universal Listings (6.0)

[lb-]

Universal Listings is a new wide ranging feature that has a different UI for most model index/listings.

Additionally there are new dialog based filtering features.

These will come in 6.0 and it would be good to highlight and update the guide accordingly.

See

• https://github.com/wagtail/wagtail/pulls?q=is%3Apr+universal+listings+is%3Aclosed (20+ PRs)
• https://github.com/wagtail/wagtail/discussions/10446
• https://github.com/wagtail/wagtail/issues/10439
• https://github.com/wagtail/roadmap/issues/33