Add the remote package

This package is extracted from platform/touch_firmware_test directly
except that an __init__.py is added to make it a package.

The remote package is very useful to get touch events through ssh
from a remote dut, either a chromebook or an android machine. The
remote package is included so as to make webplot self-contained.
In this way, webplot server can be run on a dut or on any other host
with python.

BUG=chromium:443539
TEST=manual testing

Change-Id: I2810a4e8bac7ae9437ab6a2fc0b19beeae24aeb9
Reviewed-on: https://chromium-review.googlesource.com/236837
Reviewed-by: Charlie Mooney <charliemooney@chromium.org>
Commit-Queue: Shyh-In Hwang <josephsih@chromium.org>
Tested-by: Shyh-In Hwang <josephsih@chromium.org>