autotest: Migrates network_WiFiRoaming/002Suspend to new method.

Replaces network_WiFiRoaming/002Suspend test with script and control
file in network_WiFi_RoamSuspend directory.  New code conforms to test
infrastructure changes provided to address crbug.com/224443.

Required migrating do_suspend and do_suspend_bg to new XMLRPC methods.
These commands use the power manager to suspend the DUT for a
specified number of seconds.  The '_bg' command returns control to the
caller immediately.

The test (in new and old implementations) does the following:
  - setup AP
  - suspend DUT for 10 seconds
  - verify that the DUT is still connected after resume

  - suspend DUT for 20 seconds
  - change AP frequency and BSSID
  - verify that DUT roams to new BSSID/frequency after resume

BUG=chromium:256895
TEST=autotest

Change-Id: I44af2fea27e8e723b2e72cf490f5ab3b332361b8
Reviewed-on: https://chromium-review.googlesource.com/62882
Reviewed-by: Wade Guthrie <wdg@chromium.org>
Commit-Queue: Wade Guthrie <wdg@chromium.org>
Tested-by: Wade Guthrie <wdg@chromium.org>
6 files changed