Return boxed type in unpack{Float,Double}#

In the primitives unpackFloat# and unpackDouble#, the result from
the primitive evaluator was an unboxed literal (i.e. Float#) when
the actual result of the function is a boxed literal (i.e. Float).
This led to #2097 having core that looked like

```
case 1.0# of
  F# x -> ...
```

which will rightly never match. When the primitives instead return
the correct type we get a case expression

```
case F# 1.0# of
  F# x -> ...
```

where the caseCon transformation can fire.

clash-ghc/src-ghc/Clash/GHC/Evaluator/Primitive.hs

@@ -1788,11 +1788,15 @@ ghcPrimStep tcm isSubj pInfo tys args mach = case primName pInfo of
 
   "Clash.Class.BitPack.Internal.unpackFloat#"
     | [i] <- bitVectorLiterals' args
-    -> reduce . Literal . FloatLiteral $ unpack (toBV i :: BitVector 32)
+    -> let resTy = getResultTy tcm ty tys
+           val = unpack (toBV i :: BitVector 32)
+        in reduce (mkFloatCLit val resTy)
 
   "Clash.Class.BitPack.Internal.unpackDouble#"
     | [i] <- bitVectorLiterals' args
-    -> reduce . Literal . DoubleLiteral $ unpack (toBV i :: BitVector 64)
+    -> let resTy = getResultTy tcm ty tys
+           val = unpack (toBV i :: BitVector 64)
+        in reduce (mkDoubleCLit val resTy)
 
   -- expIndex#
   --   :: KnownNat m
@@ -4186,6 +4190,30 @@ bitVectorLitIntLit tcm tys args
   | otherwise
   = Nothing
 
+mkFloatCLit :: Word32 -> Type -> Term
+mkFloatCLit lit resTy =
+  App (Prim info) (Literal (FloatLiteral lit))
+ where
+  info = PrimInfo
+    { primName = "GHC.Types.F#"
+    , primType = mkFunTy floatPrimTy resTy
+    , primWorkInfo = WorkNever
+    , primMultiResult = SingleResult
+    , primUnfolding = NoUnfolding
+    }
+
+mkDoubleCLit :: Word64 -> Type -> Term
+mkDoubleCLit lit resTy =
+  App (Prim info) (Literal (DoubleLiteral lit))
+ where
+  info = PrimInfo
+    { primName = "GHC.Types.D#"
+    , primType = mkFunTy doublePrimTy resTy
+    , primWorkInfo = WorkNever
+    , primMultiResult = SingleResult
+    , primUnfolding = NoUnfolding
+    }
+
 -- From an argument list to function of type
 --   forall n. KnownNat n => ...
 -- extract (nTy,nInt)