Add tests for usage in npm and yarn repos

[NullVoxPopuli]

To help prevent stuff like this:

• 6.1, ember-data TS config is broken in monorepo when using npm or yarn@1 ember-cli/ember-cli#10611

I'm thinking we copy a select few sample apps to a tmp directory in CI, copy some packed deps (tars), edit the package.json, and make sure stuff like type check, and a super basic test passes