menuconfig: Add jump keys to search results

makes it possible to jump directly to the menu for a configuration entry after
having searched for it with '/'. If this menu is not currently accessible we
jump to the nearest accessible parent instead. After exiting this menu, the
user is returned to the search results where he may jump further in or
elsewhere.

Signed-off-by: Benjamin Poirier <bpoirier@suse.de>
Signed-off-by: Michal Marek <mmarek@suse.cz>