[Messageport] Add Messageport implementation.

Tests are passing, but since application installation support isn't ready, it requires a few hacks for this to actually work.

This includes writing a short wrapper program that correctly passes the path to Tizen extensions, adding a mocked version of `tizen.application.getCurrentApplication()` that returns the standard `tct-messageport` package ID, installing this package, and modifying `channel-service` so that the application ID is hardcoded.