Separate permissions to allow more granular control

Problem/Motivation

I would like to restrict the ability to delete menus to certain roles, but currently, the delete permission is wrapped up in "Manage menu items" and "Manage menus", which means removing permission to create, edit and update is also removed.

Steps to reproduce

Create a menu
Alter the permissions:
"Manage menu items" and "Manage menus"
View the changes in permissions

Proposed resolution

Rather than "Manage menu items" and "Manage menus"
Could we have:
"Create menu items"
"Edit menu items"
"Delete menu items"
and also:
"Create menus"
"Edit menus"
"Delete menus"

Remaining tasks

Edit the available permissions
Update the code to respect the new permissions

User interface changes

The permissions page will be longer