Provide a backup/restore app pre-installed

### Problem

Cloud storage and back-ups are -- for many -- an "Apps you need" aspect of a modern OS.

It is currently very possible to back-up files with tools like `rsync` `grsync` or `deja dup`, but they're all a bit clunky and in no way integrated with Files.

### Proposal

Give EOS a "cloud storage" option by integrating rsync to Files.

Things this might entail:
1. A settings page for Files which shows which hosts it can access (Dropbox, Google Drive, etc, etc)
- Might also include "auto back-up scheduling" type stuff
- Might also include a list of currently "synced" folders and files
2. An addition to the right click menu of file/folder items which allows for `Sync this folder/file > Drop Box | Google Drive | My Server`
- Files/folders which are backed up might have some way of showing this information
3. Perhaps a notification or topbar icon which gives information on back up status

Imagine how nice it would be to easily back stuff up!?

### Prior Art (Optional)

I can make some art, but would like to see some feedback first.