Do {Nonce,}AppExprs need annotations?

[langston-barrett]

This is a follow-up to #244, where we observed that BoundVarExprs already carry Nonces, so there's no need to create Annotation expressions for them. As it turns out, the same is true for {Nonce,}AppExpr:

what4/what4/src/What4/Expr/App.hs

Line 111 in 076f49b

= NonceAppExprCtor { nonceExprId :: {-# UNPACK #-} !(Nonce t tp)

what4/what4/src/What4/Expr/App.hs

Line 125 in 076f49b

= AppExprCtor { appExprId :: {-# UNPACK #-} !(Nonce t tp)

Perhaps we should special-case these in the same way we did BoundVarExpr in #245.