Reorganize Navigation menu items and make them consistent with other similar pages in core

Problem/Motivation

Navigation module menu items for its settings and block layout are defined with different weights, hence they do not appear together in a clean core installation. That could be confusing for site administrators.

Proposed resolution

• Define the same weight for both menu items. Leaving the value empty to use the default value might be the preferred approach
• While we are here, rename Navigation Settings route controller and menu item to Navigation settings to be consistent with other settings pages in core
• While we are here, add a simple description to Navigation settings menu item to be consistent with other core settings menu links. A simple string like Manage navigation settings. would be enough.

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet