Ptr operations have the wrong types

For example,

```haskell
copyPtrToMutablePrimArray
:: forall m a. (PrimMonad m, Prim a)
=> MutablePrimArray (PrimState m) a
-> Int
-> Ptr a
-> Int
-> m ()
```

This accepts an arbitrary `PrimState m`, but that breaks referential transparency in `ST`, since the result of the `ST` calculation will depend on what's stored at that address at that time. All operations that dereference `Ptr` or `Addr` values should require `PrimState m ~ RealWorld`.

Start with the copyPtrToMutablePrimArray signature shown in the issue, then locate the other operations that dereference Ptr or Addr values. Check how their PrimState constraints are declared; done means all such operations require PrimState m ~ RealWorld without weakening unrelated operations.

Written by the indexing model from the issue text.