Add java reflection to hierarchy (#2209)

* Add Hierarchy trait

* Add Hierarchy trait

* Add Hierarchy scaladoc

* Add license

* Add isA and tests

* Add back isA

* Make calculate via lazy val

* Apply suggestions from code review

Co-authored-by: Megan Wachs <megan@sifive.com>

* Add shouldNot compile

* Update src/test/scala/chiselTests/experimental/hierarchy/InstanceSpec.scala

Co-authored-by: Jack Koenig <koenig@sifive.com>

* Made protected vals private

Co-authored-by: Megan Wachs <megan@sifive.com>
Co-authored-by: Jack Koenig <koenig@sifive.com>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>