Navigation: When creating submenu automatically suggest existing submenu pages.

[paaljoachim]

Is your feature request related to a problem? Please describe.
An example.

We created a menu with a lot of submenu pages.

Let's check out the navigation in Gutenberg.
I see that add existing menu is still not merged. So I add top level pages.

I click Rooting Agents -> Add Submenu. I expect the existing submenu items to show up in the recently updated suggestion screen.

Here we see only recently added and not a suggestion of existing submenu pages. As can be seen in the Appearance -> Menus -> Pages screen.

Describe the solution you'd like
I would like to be able to see a suggestion of submenu items to an existing parent menu item.

Describe alternatives you've considered
Looking up the name of the submenu items and then begin writing the first letters so they show up in the suggestion/recently added screen so that I can select them.

[jasmussen]

@shaunandrews had an idea that either in addition to, or as a feature of the incoming "Page List" block (#28265), when this block was added as a submenu block it would simply list all submenu items, and they would stay in sync when new subpages were added. I'd suggest that be the ideal way to fix this issue.

Already now, said "page list" block does add submenu items, so there's an argument to be made that that PR will fix this one.

[paaljoachim]

Thank you Joen! It looks like a very interesting block!
We can close this issue when the PR is merged.

[tellthemachines]

#28265, which adds the Page list block, has been merged. @paaljoachim can we close this issue now, or are there any remaining concerns to be addressed?