Derive `Functor` core map types
The types in question are the TrieMap
types in the following modules:
GHC.Core.Map.Expr
GHC.Core.Map.Type
GHC.Data.TrieMap
GHC.Stg.CSE
We not yet derive Functor
(rather we have written explicit instances); this is the reason.
Once #17037 is closed, we should derive these.