Spare IDisposable is added to class, when base class/interface already implements IDisposable

[BADF00D]

Prerequisites

• [x] I have written a descriptive issue title
• [x] I have verified that I am running the latest version of DisposableFixer: YOUR_VERSION
• [x] I have searched open and closed issues to ensure it has not already been reported

Description

When using a CodeFix that creates/uses a field/property to dispose in Dispose()-method, an IDisposable is added to class, regardless there is already an IDisposable at the base class/interface,

Source Code

This:

using System;
using System.IO;

namespace MyNs {
    public interface IDoSomething : IDisposable {
    }
    internal class Dummy : IDoSomething {
        private MemoryStream Stream = new MemoryStream();

        public void Dispose() { }
    }
}

Becomes

using System;
using System.IO;

namespace MyNs {
    public interface IDoSomething : IDisposable {
    }
    internal class Dummy : IDisposable, IDoSomething {
        private MemoryStream Stream = new MemoryStream();

        public void Dispose() {
            Stream?.Dispose();
        }
    }
}

But is should be:

using System;
using System.IO;

namespace MyNs {
    public interface IDoSomething : IDisposable {
    }
    internal class Dummy : IDoSomething {
        private MemoryStream Stream = new MemoryStream();

        public void Dispose() {
            Stream?.Dispose();
        }
    }
}

Screenshot

[BADF00D]

Will be part of release 1.0.0