awakens default getter synthesis from the untyper nightmare

Our happy little macro paradise is regularly invaded by resetAllAttrs,
the bane of all macros and typers. It’s so ruthless and devastating that
we’ve been long scheming to hack something really cool and to one day
defeat it.

Today we make the first step towards the happy future. Today we overthrow
the UnTyper, resetAllAttrs’s elder brother that rules in the kingdoms of
GetterLand and CaseClassia, and banish him from the land of getters.
In the name of what’s good and meta, let’s band together and completely
drive him away in a subsequent pull request!
untyper is no more

Unlike with default getters, removing untyper from case class synthesis
was trivial. Just resetLocalAttrs on a duplicate of the provided class def,
and that’s it.

resetAllAttrs, you’re next. We’ll get to you! Eventually...