Implement tab focus switching in search bar
Widget focus switching using tab/shift+tab keys. Allows to move between input field and buttons. Switching is limited to IncrementalSearchBar's children.
To test, open search bar and press tab - focus should change to next button/input. Esc key closes the bar, regardless of which input/button has the focus. Shortcut used for opening the bar (Ctrl Shift F) focuses search input field when the bar is already open and button is selected.