[CHNL-15530] Message Bus Support

[dan-peluso]

Description

Mostly logic added to the bridge.js (which I am certainly in support of making a different repo so we can import the same file for every native client we have) to support listening for the bus to be created, and then listening for each of the messages and relaying to the kotlin webview client.

Check List

• Are you changing anything with the public API?
• Are your changes backwards compatible with previous SDK Versions?
• Have you tested this change on real device?
• Have you added unit test coverage for your changes?
• Have you verified that your changes are compatible with all Android versions the SDK currently supports?

Changelog / Code Overview

Test Plan

Testing this requires some decent setup:
1 - get app running with onsite modules

2 - get fender running (using this branch) with onsite dependencies as well - should be able to publish a form in the webapp and then make it live

3 - change the HTML code to point to a local :8080 onsite instead of production, and make sure to run the following adb commands if you're running a network proxy
adb reverse tcp:8080 tcp:8080
adb reverse tcp:4001 tcp:4001

You should now be able to see the locally created form from the android test app in the 'messaging' menu. Check the logs after loading and ensure that a inAppFormsDataLoaded has come through.

Related Issues/Tickets

https://klaviyo.atlassian.net/browse/CHNL-15530