Move Wasmtime for .NET to the Wasmtime repo.

This moves the Wasmtime for .NET implementation to the Wasmtime repo.

Wasmtime for .NET is a binding of the Wasmtime API for use in .NET.

crates/misc/dotnet/src/IHost.cs

@@ -0,0 +1,25 @@
+using System;
+using System.Collections.Generic;
+using Wasmtime.Bindings;
+
+namespace Wasmtime
+{
+    /// <summary>
+    /// The interface implemented by Wasmtime hosts.
+    /// </summary>
+    public interface IHost
+    {
+        /// <summary>
+        /// The <see cref="Wasmtime.Instance" /> that the host is bound to.
+        /// </summary>
+        /// <remarks>A host can only bind to one module instance at a time.</remarks>
+        Instance Instance { get; set; }
+
+        /// <summary>
+        /// Gets the import bindings of the host given a WebAssembly module.
+        /// </summary>
+        /// <param name="module">The WebAssembly module to get the import bindings for.</param>
+        /// <returns>Returns the list of import bindings for the host.</returns>
+        List<Binding> GetImportBindings(Module module) => Binding.GetImportBindings(this, module);
+    }
+}