Discover and index network folders

[dfs-minded]

The user should be able to select in GUI to index discovered network drives.

There might be issues with permissions: to access MFT you need administrative rights on that machine, so maybe also give a hint to the user if they do not have permissions for that.

One more question to address is how to listen to the update journal events (maybe easy, but maybe will need some workaround to fetch the updates).