[Navigation block] Lift the limit of 10 pages max when creating navigation from top level pages

[adamziel]

Description

As reported in #19266:

In the Navigation block, if there are more than 10 top level pages and you choose Create from all top level pages then you only get the first 10, ordered by post ID.

This PR lifts this restriction by setting per_page: -1. It's actually also a good opportunity to discuss - should we still have a fixed limit of e.g. 50 pages? I don't see how navigation consisting of 200 top level pages would be any useful.

How has this been tested?

Tested locally

Screenshots

Types of changes

Non-breaking changes

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR.

[draganescu]

Wouldn't the best for this case be if we had a default which can be changed via a filter? Usually it's ok to have some opinionated default that has less chances to break a layout with the click of a button.

What if we have a default of 10 and change the label to Craete from most recent 10 top level pages or something and have these filterable :)

Seems like a lot of work of an edge case tho ...

[kadamwhite]

From a REST API standpoint, I believe we should still cap the max items returned per-request, but should up that limit so that fewer iterative requests are necessary. (see #21212)