appDisplay: Fix focus path when edit is enabled

appDisplay: Fix focus path when edit is enabled

When an app folder is open and its panel is shown, there are
three main elements: the folder name, the list of apps, and the
Edit togglebutton. By default, the user can use TAB to jump
between the app icons and the Edit togglebutton, but when the
togglebutton is checked, the folder name becomes editable and
the focus jumps to it.

Unfortunately, if the user goes out of the editable name with
TAB, the focus only cycles between the Edit togglebutton and
the app icons, never landing over the editable folder name (which
remains editable until the Edit togglebutton is unchecked).

This patch fixed this, making the editable folder name focusable
when using TAB, as expected, when the Edit togglebutton is
checked.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/4116>