Ensure Ember Octane compatibility

[auvipy]

No description provided.

[shamrt]

A year-and-a-half later, I'm working on this, and plan to submit a PR in the next little bit.

It'll be a breaking change, but that's the nature of moving from classic components to Glimmer 🤷

[shamrt]

As mentioned in #62, turns out migrating to Glimmer was technically infeasible, so I did the next best thing: updated the addon to Ember v3.18 and added a feature for providing arbitrary mixin props to the component wrapper.

[shamrt]

If anyone wants to use the results of this modernization before it is merged into upstream and published, I've published a fork in my company's npm org: https://www.npmjs.com/package/@rewardops-forks/ember-react-components. If and when @alexlafroscia accepts my PR, we plan to switch back to his package.