screenshot: Handle a missing recent-files history

screenshot: Handle a missing recent-files history

On a profile without recently-used.xbel, taking a screenshot saves the PNG
but does not add it to recent files. GLib.BookmarkFile.load_from_file()
reports a missing file as GLib.FileError.NOENT, while the handler checked
GLib.BookmarkFileError.FILE_NOT_FOUND and returned.

Fixes: b89d90eb80 ("screenshot: Use GLib.BookmarkFile to save recent screenshots")
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/4405>
(cherry picked from commit fa82d28c3b0dcfd27e49bac291b37b5ca9237dc7)