Fetch functions of atomic_ptr calls atomic intrinsics functions with pointer-type arguments (invalid_mut), which will cause typecheck failures.
The change in this commit add support of pointer-type arguments into codegen_atomic_binop to fix the issue.
The new codegen_atomic_binop will cast pointer arguments to size_t, apply op on them, and then cast the op result back to the pointer type.

Fix the issue model-checking#3042.

Co-authored-by: Zyad Hassan <88045115+zhassan-aws@users.noreply.github.com>