[autotest] Modify control_data.py to parse ATTRIBUTES from control files

Modify control_data.py to parse ATTRIBUTES list from control files.
Also, add unittest for it.

BUG=chromium:470015
TEST=Test on moblab

Change-Id: I18c59fed948b76d86b5bde8e22c1a73e5faf93d2
Reviewed-on: https://chromium-review.googlesource.com/262931
Reviewed-by: Aviv Keshet <akeshet@chromium.org>
Reviewed-by: Shuqian Zhao <shuqianz@chromium.org>
Tested-by: Shuqian Zhao <shuqianz@chromium.org>
Commit-Queue: Shuqian Zhao <shuqianz@chromium.org>
2 files changed