Propose UI improvements to the recycle bin feature

In the early roadmap brainstorming sessions one of the items was about giving admins more control over the Recyble Bin. This was already asked by some clients and it could indeed have significant impact on the overall UX of XWiki.

Some improvements already discussed:

Admin UI:

• Add options for configuring the periodicity of cleans
• Add a value showing how much space the recycle bin is taking
• shortcut to the recycle bin itself (list of documents)

On the list itself:

• Add a reverse link to the Admin UI
• Add batch operations (cleaning, restoring)

But other improvements could be found during UX analysis.