Show additional (higher) levels in the file tree view on file pages

Created by: Joelkw

This customer initiated this request.

On the file tree view (panel to the left when viewing a file), we currently show you the directory your file is in and let you expand all sub-directories, but you can't navigate higher in the tree. There are times when users want to look at the directory structure of the entire repo and browse other files.

One note – we don't re-load the file view right now, so if you start at a higher-directory file and navigate to a lower-directory file in this view, it still shows higher-level directories.

The view in question:

Direct feedback: "Basically getting to the top level of the repo will be sufficient. Currently when jumping to files with go to definition the default is to show only the most inner directory of the file that I jumped to which makes it hard to understand its context or navigate to nearby other files."