Navigate to filesystem root

Coming from emacs + helm, it would be fantastic to be able to quickly navigate to the root of the filesystem. Right now the quickest way I've figure out is to type `~/`, `Left Arrow`, `Left Arrow`. Ideally I'd like to simple type `/` and have that go to the root instead of assuming I mean a path under the current project.

Start by locating the file-browser navigation entry point that handles typed paths, then reproduce the current `~/`, Left Arrow, Left Arrow workaround and test typing `/`. Done means `/` navigates to the filesystem root instead of being treated as a path under the current project.

Written by the indexing model from the issue text.