[feature request] Tabs in Files

[ArtificialOwl]

In case of a rewrite of the Files App, it would be interesting to imagine the development to allow some cool features:

• Tabs. This is more of a front-end feature. Tabs can be available at the top of the page, or (better) using the left panel.
  Each tab will display the content of a different folder and drag 'n drop should be doable from on tab to another. An API would allow any app to create a new Tab.

• Virtual Folder. Back-end. Any app can fill a Model with a group of Node (folders and file) that will be display as a folder on the front-end.

Both feature are complementary, an App create a new Tab with enough parameters so that when retrieving result from the server, the request will be fed by the right app.

@skjnldsv