Problem/Motivation
Navigation Blocks page (/admin/config/user-interface/navigation-block) is the place to go to edit the navigation layout and manage the blocks to be included there.
Current NavigationSectionStorage::access() implementation just gives free access to the page. That added to logic in LayoutBuilderAccessCheck::access() ends up being just like checking for configure any layout permission.
That permission is not very restrictive nor representative for Navigation module.
Would be great to have a more representative and intituive way to manage access to that page.
Proposed resolution
Create a new Administer Navigation Layout permission
Override NavigationSectionStorage::access() to check for that permission
Add handles_permission_check to NavigationSectionStorage class attributes to not grant access based on configure any layout permission.
Remaining tasks
Implement changes.
Add tests.
User interface changes
None
API changes
New permission added.