[autotest] Allow gs_offloader to limit the number of files in a result folder

If the number of files is too big, try to compress each subfolder.

BUG=chromium:537756
TEST=unittest

Change-Id: I833c2664c27bc566d08a0354ea4f2695dec2ec36
Reviewed-on: https://chromium-review.googlesource.com/304090
Commit-Ready: Dan Shi <dshi@chromium.org>
Tested-by: Dan Shi <dshi@chromium.org>
Reviewed-by: Simran Basi <sbasi@chromium.org>
4 files changed