Add the option to view the rights set in wiki

[ChiuchiuSorin]

Create a new modal or page in which to display all specific rights set in wiki.

[oanat]

Some extensions and snippets already exist to check rights and it would be best to have a global tool in one place:

• Check Security Cache (well -established)
• Check Rights For A User On A Page
• List Pages With Rights
• Transfer Rights (well -established)
  Well-established scripts could be integrated as is.

[snazare]

Note: aside from inserting the feature that existed in the previous admin tools application and the ones mentioned above, please also make the show rights request async, so that the response is downloaded. This is needed as multiple clients have a timeout set (let's say 1 minute) and the rights request may take more. If this happens, the list of rights is never obtained.

[lucaa]

@snazare maybe we can add this feature for now, synchronous as it was, and then, as an improvement, make it work for short timeouts . I wouldn't want an improvement block the presence of the feature alltogether as it's very useful. Maybe we can add a warning on the page that it takes long and depending on the server settings may result in a timeout error.