Detect wrong usages of callInfo argument access

[tpodolak]

Analyzers should be able to detect common mistakes when accessing invocation arguments via CallInfo.

using System;
using NSubstitute;

namespace MyNamespace
{
    public interface Foo
    {
        int Bar(int x);
    }

    public class Bar
    {
    }

    public class FooTests
    {
        public void Test()
        {
            var substitute = NSubstitute.Substitute.For<Foo>();
            substitute.Bar(Arg.Any<int>()).Returns(callInfo =>
            {
                var x = (Bar)callInfo[0]; // invalid cast
                var xx = callInfo[0] as Bar; // invalid cast
                var xxx = (Bar)callInfo.Args()[0]; // invalid cast
                var xxxx = callInfo.Args()[0] as Bar; // invalid cast
                var xxxxx = callInfo[1]; // out of bounds
                var xxxxxx = callInfo.Args()[1]; // out of bounds
                var xxxxxxx = callInfo.ArgTypes()[1]; // out of bounds
                callInfo[0] = 1; // no ref or out method
                callInfo[0] = new object(); //  no ref or out method, wrong type assigned
                return 1;
            });
        }
    }
}