Debug 1 -- load up a compiler by reflection

Follow the procedure used in [`sbt-exercise`](https://github.com/scala-exercises/sbt-exercise/blob/main/sbt-exercise/src/main/scala/org/scalaexercises/exercises/sbtexercise/ExerciseCompilerPlugin.scala#L145), but don't use the doc extraction global at the root -- just use a plain global