File name on export should contain only the page name

Currently, when exporting a page in office or pdf, the filename that is proposed to the browser / user is composed from the full reference of the page:

• including the wiki name, including for XWiki instances having a single wiki
• including the WebHome particle at the end, for non-terminal pages
• including the whole path of the page on the wiki (all parents from the page tree)

Ideally, the name of the file should be made out of the name of the page that gets exported:

• without WebHome
• without the name of the wiki - at least if the XWiki instance is single wiki
• without the path - parents
  • I agree that this part is arguably useful and we may want to keep it

Even if this can endup in the export of XWiki proposing the same filename for 2 different pages in the wiki, the user that is asking for the export can be responsible on handling unicity when saving the file, if they wish so. In any case, the user has the control over the file name, so unicity is actually in their hands, this issue is only about having a more reasonable filename proposed by XWiki.

If this needs to be a configuration, it can be a configuration.