gs_archive_server: modify extract rpc to return bin file data

The extract RPC in gs_archive_server was originally written to return
text file data. This usage is deprectaed due to high level design
changes. This CL updates this RPC to return bin data extracted from a
tar file.

BUG=chromium:1077131
TEST=Manually tested on chromeos2-devservertest

Change-Id: I0c142f645c15285ad00c0c0edcc1d88dc69cf2df
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/2207529
Tested-by: Sanika Kulkarni <sanikak@chromium.org>
Commit-Queue: Sanika Kulkarni <sanikak@chromium.org>
Auto-Submit: Sanika Kulkarni <sanikak@chromium.org>
Reviewed-by: Congbin Guo <guocb@chromium.org>
3 files changed