Add a composer.json file so that dependent modules can reference this project

Problem/Motivation

This is an API module and is required by projects that reference it. Users of those modules would like to install their target module and automatically get all the dependencies using composer.

Steps to reproduce

None. Just note that there is no composer.json file in this repo.

Proposed resolution

Add a composer.json file to this reop.

Remaining tasks

Add the file. Make sure test process is not affected.

User interface changes

None.

API changes

None.

Data model changes

None.