Mike/fix embroider

[LevelbossMike]

Fixes embroider compatibility.

To make sure the addon works with embroider I added another test-app v4-embroider that uses the addon from an Ember v4 application that has embroider turned on for building the application.

Reasons why this didn't work under embroider.

1. We need to make ember-auto-import(v2) a dependency of the addon itself
2. We need to declare xstate a devDependency as well as a peerDependency on the addon otherwise imports from addon code will fail when including ember-statecharts in an embroider build 🤷
3. ember-qunit-assert-helpers broke the test-suite when run under embroider

This PR also introduces turborepo and pnpm for easier handling of the monorepo.

All of this can probably be improved but for now it looks like an ok fix for the issue we were experiencing with embroider.