vboot/ui: implement language selection screen

Implement language selection screen, and add language item to all the
other screens. Add a default screen init function default_screen_init()
to initialize the default selection to the second item if the first item
is the language selection.

BUG=b:146399181, b:144968920
TEST=make runtests
TEST=USE="menu_ui" emerge-nami depthcharge

Cq-Depend: chromium:2193151, chromium:2192508
Change-Id: I3251b0095ec29ec26cc27745b1089e60894c892c
Signed-off-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2196095
Reviewed-by: Joel Kitching <kitching@chromium.org>
7 files changed