Add a tool to check the state of all objects of a given type on a document on all the wikis of a farm

The idea is to be able to check the objects on a document on all wikis of a farm. Its purpose would be to be able to check state of a document before importing something on top of it (using the farm importer). Can be used to check:

• state of rights on a document (e.g. to compare the rights of the farm at 2 moments in time, or to check that no new custom rights were added on a given page)
• state of comments on a document - to check whether a new version of the document can be imported on top or there are new comments that users have added on that document.

This tool wouldn't be changing anything, would only be displaying the state.