Restrict script right to the wiki level

Currently, script right can be granted both on the page and the wiki level. Script right on a space level doesn't make much sense as what you can do in a script doesn't depend on the space in which it is written. It is not even true that scripts are only active when a space is accessed as scripts can also be in titles which are displayed across the wiki (e.g., in the navigation or recent changes). Further, script right is a powerful and dangerous right, making it only possible to grant this right on the wiki level makes it easier to control it.

At the same time, with this change, space admin right will no longer imply script right. This is useful as it should be possible to administer a space without having script right.

See also the discussion in the forum.