introduce lerna-changelog

[ghost]

I think we should establish a standard release process for adopted ember addons. This PR introduces a few dependencies to try this idea out.

Based on others work to manage OSS projects and @katiegengler's advice, I propose we use lerna-changelog combined with release-it. See the following projects for example lerna-changelog changelogs and usage:

• ember-cli-babel
  * karma
• qunit-dom

mnunmununm recommended we use lerna version directly. I think that is a great idea, but it requires you to follow conventional commits.. I think that introduces too much overhead for the loosely structured nature of contributing to adopted ember addons.

[kategengler]

To be clear, the karma changelog is an example of conventional-changelog not lerna-changelog