Remove the Navigation Editor Screen

[getdave]

We should remove the code that comprises the experimental Navigation Editor screen (i.e. @wordpress/edit-navigation package).

@getdave, if the Navigation Screen has been removed, does that mean we could review and close pretty much all the open related issues?

I think that's reasonable.

Originally posted by @getdave in #40878 (comment)

[getdave]

What do you think @draganescu @talldan @scruffian?

[draganescu]

I am all for this. It is very likely that we'll never use this as a basis for whatever ends up as being a stand alone editor for the navigation block.

[getdave]

cc @mrfoxtalbot @annezazu

[annezazu]

Noting that I've already moved this to "inactivate" for the feature projects page and can always list at as closed too.

[scruffian]

I agree, let's remove.