vboot/ui: Implement debug info screen

Implement debug info screen with multiple pages.

The debug info screen can be accessed using TAB as keyboard shortcut.
The menu navigation will be added in a separate CL.

The screen has one textbox for displaying one page of debug info,
and three buttons: page up, page down, and back.

BUG=b:146399181, b:144969088
     make clean && make runtests
TEST=USE="menu_ui" emerge-nami depthcharge
     press tab, observe the debug info on the screen

Cq-Depend: chromium:2251685
Signed-off-by: Hsuan Ting Chen <roccochen@chromium.org>
Change-Id: I6bc0a49c4d69817825f35435b643b006823b5c03
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2251868
Reviewed-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-by: Joel Kitching <kitching@chromium.org>
9 files changed