Add factory methods and extension methods for wrapping System.IDisposable objects

[konard]

Summary

This PR addresses issue #23 by adding factory methods and extension methods that enable easy wrapping of System.IDisposable objects in the Platform's disposable wrappers.

Changes Made

1. Factory Methods

• Added Disposable.Create(System.IDisposable) static method
• Added Disposable.Create(System.IDisposable) static method
• Added Disposable<TPrimary, TAuxiliary>.Create((System.IDisposable, System.IDisposable)) static method

2. Extension Methods

• Added AsDisposable() extension method to wrap System.IDisposable in Disposable
• Added AsDisposableContainer() extension method to wrap System.IDisposable in Disposable<System.IDisposable>

3. Test Coverage

• Added comprehensive unit tests covering all new factory and extension methods
• All tests verify proper disposal behavior and object reference handling

Usage Examples

// Using factory methods
var fileStream = new FileStream("test.txt", FileMode.Create);
var wrapper1 = Disposable.Create(fileStream);
var wrapper2 = Disposable<System.IDisposable>.Create(fileStream);

// Using extension methods
var timer = new Timer();
var wrapper3 = timer.AsDisposable();
var wrapper4 = timer.AsDisposableContainer();

// Wrapping multiple disposables
var stream1 = new MemoryStream();
var stream2 = new MemoryStream();
var multiWrapper = Disposable<System.IDisposable, System.IDisposable>.Create((stream1, stream2));

Note on Implementation Approach

Initially attempted to use implicit operators, but C# doesn't allow user-defined conversions to or from interfaces (CS0552). The current implementation using factory methods and extension methods provides a clean, discoverable API while avoiding compiler limitations.

Fixes #23