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/Module.cs

@@ -0,0 +1,101 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Wasmtime
+{
+    /// <summary>
+    /// Represents a WebAssembly module.
+    /// </summary>
+    public class Module : IDisposable
+    {
+        internal Module(Store store, string name, byte[] bytes)
+        {
+            if (store.Handle.IsInvalid)
+            {
+                throw new ArgumentNullException(nameof(store));
+            }
+
+            var bytesHandle = GCHandle.Alloc(bytes, GCHandleType.Pinned);
+
+            try
+            {
+                unsafe
+                {
+                    Interop.wasm_byte_vec_t vec;
+                    vec.size = (UIntPtr)bytes.Length;
+                    vec.data = (byte*)bytesHandle.AddrOfPinnedObject();
+
+                    Handle = Interop.wasm_module_new(store.Handle, ref vec);
+                }
+
+                if (Handle.IsInvalid)
+                {
+                    throw new WasmtimeException($"WebAssembly module '{name}' is not valid.");
+                }
+            }
+            finally
+            {
+                bytesHandle.Free();
+            }
+
+            Store = store;
+            Name = name;
+            Imports = new Wasmtime.Imports.Imports(this);
+            Exports = new Wasmtime.Exports.Exports(this);
+        }
+
+        /// <summary>
+        /// Instantiates a WebAssembly module for the given host.
+        /// </summary>
+        /// <param name="host">The host to use for the WebAssembly module's instance.</param>
+        /// <returns>Returns a new <see cref="Instance" />.</returns>
+        public Instance Instantiate(IHost host)
+        {
+            if (host is null)
+            {
+                throw new ArgumentNullException(nameof(host));
+            }
+
+            if (host.Instance != null)
+            {
+                throw new InvalidOperationException("The host has already been associated with an instantiated module.");
+            }
+
+            host.Instance = new Instance(this, host);
+            return host.Instance;
+        }
+
+        /// <summary>
+        /// The <see cref="Store"/> associated with the module.
+        /// </summary>
+        public Store Store { get; private set; }
+
+        /// <summary>
+        /// The name of the module.
+        /// </summary>
+        public string Name { get; private set; }
+
+        /// <summary>
+        /// The imports of the module.
+        /// </summary>
+        public Wasmtime.Imports.Imports Imports { get; private set; }
+
+        /// <summary>
+        /// The exports of the module.
+        /// </summary>
+        /// <value></value>
+        public Wasmtime.Exports.Exports Exports { get; private set; }
+
+        /// <inheritdoc/>
+        public void Dispose()
+        {
+            if (!Handle.IsInvalid)
+            {
+                Handle.Dispose();
+                Handle.SetHandleAsInvalid();
+            }
+        }
+
+        internal Interop.ModuleHandle Handle { get; private set; }
+    }
+}