Add infrastructure for Interactive tests

Inspired by the SemiAuto tests used by the test team, this uses a
similar approach but wrapped in an XML-RPC server deployed to the
client.

BUG=chromium:256771
TEST=server test that uses interactive_client

Change-Id: I8420a2a2ed6fc031b97044d6bbcf32e50cbcf4a4
Reviewed-on: https://gerrit.chromium.org/gerrit/63640
Reviewed-by: Simran Basi <sbasi@chromium.org>
Commit-Queue: Scott James Remnant <keybuk@chromium.org>
Tested-by: Scott James Remnant <keybuk@chromium.org>
7 files changed