Replace serial support by USB code for Twinkie

Transform the terminal into a USB-serial terminal from the Chromium Twinkie
dongle :
- replace the chrome.serial interface by an interface based on chrome.usb
  handling a console on a pair of bulk USB endpoints.
- add permissions and USB IDs for the Twinkie dongle.
- replace icons and strings by the "Twinkie Term" version.

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>