Make permission to clone node independent from permission to create a new node

Problem/Motivation

Right now it's only possible to clone a node if you have the permission to create a node of given bundle. But there are use cases where those permissions should be independent from each other. E.g. when you have nodes that can be used as template for restricted editors.

Proposed resolution

The patch i provided only removes the check for `create $bundle content`. But I think a more sophisticated solution, e.g. some extra setting, would provide a better solution in general.