Menus screen: quick search input event needs to be delegated

[afercia]

On the menus screen, the post and taxonomies boxes on the left have a "search" tab. Go in one of those, and submit a search to get some results:

Now go on the previous tab "View All" and click a couple times on the pagination links (be sure to have more than 50 posts/pages or categories otherwise the pagination links won't show up):

Then go back to the search tab and submit a new search: nothing happens.

[afercia]

In 38799:

Menus: Fix the posts-categories quick search.

On the Menus screen, events that trigger the posts-categories search need to be
delegated. This "boxes" may get dynamically rebuilt so events directly attached
to the search input field need to be delegated.

Fixes #38324.