Document template provider display and edit should be improved (usability and explanations)

Following is a list of potential improvements

• allow i18n of the template name (also see XWIKI-6617)
• when in view mode, the template should be displayed as a link
• action info should be displayed only in edit mode, as all the field explanations are (see XWIKI-6551 for details about action)
• space list explanation should be displayed as a field explanation, not as an info, for consistency