new_variant: add support for Guybrush

Add support for creating new variants of Guybrush, specifically
'guybrush'.

BUG=b:195354362
TEST=`new_variant_fulltest.sh guybrush && echo PASS`

Change-Id: If1a8c8edc8382a2071da9653692e1b55abb974b5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/3075256
Commit-Queue: Paul Fagerburg <pfagerburg@chromium.org>
Tested-by: Bhanu Prakash Maiya <bhanumaiya@google.com>
Auto-Submit: Bhanu Prakash Maiya <bhanumaiya@google.com>
Reviewed-by: Paul Fagerburg <pfagerburg@chromium.org>
4 files changed