build_image: detect compression used with toolchain packages

We'll be switching from bzip2 to zstd at some point, so have this code
detect & use the right tool automatically.

BUG=b:187789829
TEST=CQ passes

Change-Id: Ifcf14ceac0b5d79836fa61b8807496929dff9f6b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/3582874
Reviewed-by: Chris McDonald <cjmcdonald@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
3 files changed