[autotest] Add shim around site_wlan scripts.

To enable the development of WiFiInterop tests without adding dependencies
on the to-be-refactored code in client/common_lib/cros/site_wlan/ we are
adding an API around those tools.

BUG=chromium-os:35822
TEST=run new network_WiFiInterop/control.* tests on a real device.

Change-Id: I3c848b08f442cc249900602176bf6b6a1b5a901a
Reviewed-on: https://gerrit.chromium.org/gerrit/37465
Commit-Ready: Chris Masone <cmasone@chromium.org>
Reviewed-by: Chris Masone <cmasone@chromium.org>
Tested-by: Chris Masone <cmasone@chromium.org>
11 files changed