feat: Added support for struct reference index access

[CatchABus]

This PR adds functionality for creating a Reference array of structs to fill a pointer with. e.g.

        const structs = [
            new TNSSimpleStruct({x: 1, y: 2}),
            new TNSSimpleStruct({x: 3, y: 4}),
            new TNSSimpleStruct({x: 5, y: 6})
        ];
        const length = structs.length;
        const ptr = interop.alloc(interop.sizeof(TNSSimpleStruct) * length);

        const ref = new interop.Reference(TNSSimpleStruct, ptr);
        for (let i = 0; i < length; i++) {
            ref[i] = structs[i];
        }

We are still missing handling for objc classes but I think this is a good starting point.
Fixes/Closes #86