Set security update label in framework

GmsCore will use different filenames to distinguish a security update
from a normal update. (update.zip for normal update and update_s.zip for
security update.) So, if framework observes the filename as
"update_s.zip", write command "--security" to BCB. This cmd ask the
recovery image to choose the right background string for update.

Bug: 27837319
Change-Id: I2ef12267a6be57d8a81f7f9f34c09aea54530c1f