Dereferencing of input parameters doesn't work in forward mode

[guitargeek]

This is related to #961, only that now the dereferenced array is a parameter to the function.

Reproducer:

// Compile with clang++ -std=c++11 -fplugin=install/clad.so -I./install/include cladIssue.cxx -o cladIssue

#include "clad/Differentiator/Differentiator.h"

#include <iostream>
#include <vector>

double wrapper(double* params, double const* constants) {
   double c0 = *constants;
   return params[0] * c0;
}

int main()
{
   auto diff = clad::differentiate(wrapper, "params[0]"); // doesn't work
   auto grad = clad::gradient(wrapper, "params"); // works!

   double x = 2.0;
   double y = 2.0;
   double result = 0.0;
   grad.execute(&x, &y, &result);

   std::cout << result << std::endl;
   std::cout << diff.execute(&x, &y) << std::endl;
}

Compiler output:

error: indirection requires pointer operand ('int' invalid)
1 error generated.

I'm using LLVM and Clang 16 to build clad standalone (see #973).