futility: update: load quirks from firmware image CBFS file

The firmware updater now looks at CBFS 'FW_MAIN_A' (RW A) and if a text
file 'updater_quirks' is found, the contents will be fetched to setup
default quirks.

This helps sharing same customization across multiple firmware images
(for different models) shared by same unibuild OS image.  Without that,
we have to maintain a large list of hard-coded model names in firmware
updater source.

BRANCH=none
BUG=b:169284414
TEST=make runtests

Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Change-Id: I938bffe9f16bc3adee0dc3efb6976efe581c6d8c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2426093
Reviewed-by: Karthikeyan Ramasubramanian <kramasub@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2488672
Reviewed-by: Evan Green <evgreen@chromium.org>
Commit-Queue: Karthikeyan Ramasubramanian <kramasub@chromium.org>
Tested-by: Karthikeyan Ramasubramanian <kramasub@chromium.org>
4 files changed