Replace mem macros renaming (#2243)

* ReplaceMemMacros: add target rename test case

* ReplaceMemMacros: rename references to instances

* fix renaming for deduped mems

* use grouped DummyAnnos to preserve order

* Apply suggestions from code review

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

* run scalafmt

* flatten targets

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