This reverts commit c2657807be96bc6aecfc34781ca6963477b1fe29.

If we want to do this, we'll need to do it more systematically to
avoid breaking the build and confusing people who may be used to
finding the solution in a particular place.

- makes it easier to work on a solution when you can one-step define the source root containing the example.
- one step toward making it easy to run unit tests against example solutions in CI.