vboot: stop using StrnAppend and Uint64ToString

Use snprintf instead.  Remove utility_string library.
Also, prepare VbDisplayDebugInfo to handle 64-byte nvdata.

BUG=b:124141368, chromium:968464
TEST=make clean && make runtests
TEST=boot with 16-byte nvdata, check <TAB> output (one line)
TEST=boot with 64-byte nvdata, check <TAB> output (five lines)

Change-Id: If6c4b3a4e9fa7b71cb2d8ca7ccd37e4f36b97fd6
Signed-off-by: Joel Kitching <kitching@google.com>
Cq-Depend: chromium:2122061
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2104880
Tested-by: Joel Kitching <kitching@chromium.org>
Commit-Queue: Joel Kitching <kitching@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
40 files changed