Add IVS output to exported configuration files

[alextyner]

Is your feature request related to a problem? Please describe.
Configuration files write livestream and video-on-demand resource properties, but do not support ivs resources yet.

Describe the solution you'd like
Similarly to the other resource types, write the IVS output URL to configuration files on each platform.

Possible JavaScript project configuration:

% cat src/aws-video-exports.js 
// WARNING: DO NOT EDIT. This file is automatically generated by AWS Amplify. It will be overwritten.

const awsvideoconfig = {
    "myinteractivestream": {
        "aws_video_outputUrl": "https://###"
    }
};

export default awsvideoconfig;

Possible iOS/Android project configuration:

% cat app/src/main/res/raw/amplifyvideoconfiguration.json
{
    "video": {
        "plugins": {
            "awsVideoPlugin": {
                "myinteractivestream": {
                    "type": "INTERACTIVE",
                    "outputUrl": "https://###"
                }
            }
        }
    }
}

A concern: it could potentially be difficult to tell when reading the JS config whether a resource is On-Demand or Interactive. As a result, it would be the responsibility of the user to know what their video resources are named.