Validate and test packaged version of libraries

We currently have no automated tests for the actual npm package we produce. We should, at the very least, run our e2e tests against the real packages.

It would additionally be good to test the components against an Angular CLI application. It might be best, then, to change our e2e app to be an Angular CLI application.

Some other possibilities worth discussion:
- [ ] Creating a general `angular-package-validator` tool that we could use for all Angular-related projects.
- [ ] Clone and run the tests for angular.io and/or material.angular.io with the packages

_Other related checks_

* Ensure that the release doesn't include `cdk/testing` or `material/testing`

Open to other ideas here.

cc @josephperrott