file chooser: Improve search focus handling
file chooser: Improve search focus handling

Move focus to list when search results appear to make it
possible to select the first search result by just hitting
Enter. To keep this from interfering with keynav, we need
to make sure that we still handle Escape to search. And when
search comes up empty, we need to move the focus back to the
entry.

https://bugzilla.gnome.org/show_bug.cgi?id=755926

alexlarsson/gtk,grubersjoe/adwaita,alexlarsson/gtk,alexlarsson/gtk,alexlarsson/gtk,alexlarsson/gtk,alexlarsson/gtk,grubersjoe/adwaita,alexlarsson/gtk,grubersjoe/adwaita,alexlarsson/gtk,grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita