Move all interop code under Interop namespace

Move all the platform specific interop code to the `Interop` namespace
and also group the P/Invoke calls into classes representing the
modules/libraries/headers the original C functions live in.

Author: mjcheetham

src/shared/Microsoft.Git.CredentialManager.Tests/Commands/EraseCommandTests.cs

@@ -2,7 +2,6 @@
 // Licensed under the MIT license.
 using System.Threading.Tasks;
 using Microsoft.Git.CredentialManager.Commands;
-using Microsoft.Git.CredentialManager.SecureStorage;
 using Microsoft.Git.CredentialManager.Tests.Objects;
 using Moq;
 using Xunit;

src/shared/Microsoft.Git.CredentialManager.Tests/Commands/StoreCommandTests.cs

@@ -2,7 +2,6 @@
 // Licensed under the MIT license.
 using System.Threading.Tasks;
 using Microsoft.Git.CredentialManager.Commands;
-using Microsoft.Git.CredentialManager.SecureStorage;
 using Microsoft.Git.CredentialManager.Tests.Objects;
 using Moq;
 using Xunit;

src/shared/Microsoft.Git.CredentialManager.Tests/SecureStorage/MacOSKeychainTests.cs renamed to src/shared/Microsoft.Git.CredentialManager.Tests/Interop/MacOS/MacOSKeychainTests.cs

@@ -2,9 +2,9 @@
 // Licensed under the MIT license.
 using System;
 using Xunit;
-using Microsoft.Git.CredentialManager.SecureStorage;
+using Microsoft.Git.CredentialManager.Interop.MacOS;
 
-namespace Microsoft.Git.CredentialManager.Tests.SecureStorage
+namespace Microsoft.Git.CredentialManager.Tests.Interop.MacOS
 {
     public class MacOSKeychainTests
     {

src/shared/Microsoft.Git.CredentialManager.Tests/SecureStorage/WindowsCredentialManagerTests.cs renamed to src/shared/Microsoft.Git.CredentialManager.Tests/Interop/Windows/WindowsCredentialManagerTests.cs

@@ -2,9 +2,9 @@
 // Licensed under the MIT license.
 using System;
 using Xunit;
-using Microsoft.Git.CredentialManager.SecureStorage;
+using Microsoft.Git.CredentialManager.Interop.Windows;
 
-namespace Microsoft.Git.CredentialManager.Tests.SecureStorage
+namespace Microsoft.Git.CredentialManager.Tests.Interop.Windows
 {
     public class WindowsCredentialManagerTests
     {

src/shared/Microsoft.Git.CredentialManager/Application.cs

@@ -4,7 +4,6 @@
 using System.ComponentModel;
 using System.Threading.Tasks;
 using Microsoft.Git.CredentialManager.Commands;
-using Microsoft.Git.CredentialManager.SecureStorage;
 
 namespace Microsoft.Git.CredentialManager
 {

src/shared/Microsoft.Git.CredentialManager/CommandContext.cs

@@ -5,7 +5,8 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Text;
-using Microsoft.Git.CredentialManager.SecureStorage;
+using Microsoft.Git.CredentialManager.Interop.MacOS;
+using Microsoft.Git.CredentialManager.Interop.Windows;
 
 namespace Microsoft.Git.CredentialManager
 {

src/shared/Microsoft.Git.CredentialManager/Commands/EraseCommand.cs

@@ -2,7 +2,6 @@
 // Licensed under the MIT license.
 using System;
 using System.Threading.Tasks;
-using Microsoft.Git.CredentialManager.SecureStorage;
 
 namespace Microsoft.Git.CredentialManager.Commands
 {

src/shared/Microsoft.Git.CredentialManager/Commands/GetCommand.cs

@@ -2,7 +2,6 @@
 // Licensed under the MIT license.
 using System.Collections.Generic;
 using System.Threading.Tasks;
-using Microsoft.Git.CredentialManager.SecureStorage;
 
 namespace Microsoft.Git.CredentialManager.Commands
 {

src/shared/Microsoft.Git.CredentialManager/GitCredential.cs renamed to src/shared/Microsoft.Git.CredentialManager/Credential.cs

@@ -6,33 +6,46 @@
 
 namespace Microsoft.Git.CredentialManager
 {
+    /// <summary>
+    /// Represents a simple credential; user name and password pair.
+    /// </summary>
+    public interface ICredential
+    {
+        /// <summary>
+        /// User name.
+        /// </summary>
+        string UserName { get; }
+
+        /// <summary>
+        /// Password.
+        /// </summary>
+        string Password { get; }
+    }
+
     /// <summary>
     /// Represents a credential (username/password pair) that Git can use to authenticate to a remote repository.
     /// </summary>
-    public class GitCredential : SecureStorage.ICredential
+    public class GitCredential : ICredential
     {
         public GitCredential(string userName, string password)
         {
             UserName = userName;
             Password = password;
         }
 
-        /// <summary>
-        /// User name.
-        /// </summary>
         public string UserName { get; }
 
-        /// <summary>
-        /// Password.
-        /// </summary>
         public string Password { get; }
+    }
 
+    public static class CredentialExtensions
+    {
         /// <summary>
-        /// Returns the base-64 encoded, {username}:{password} formatted string of this `<see cref="GitCredential"/>`.
+        /// Returns the base-64 encoded, {username}:{password} formatted string of this `<see cref="ICredential"/>`.
         /// </summary>
-        public string ToBase64String()
+        public static string ToBase64String(this ICredential credential)
         {
-            string basicAuthValue = string.Format(CultureInfo.InvariantCulture, "{0}:{1}", UserName, Password);
+            string basicAuthValue = string.Format(CultureInfo.InvariantCulture, "{0}:{1}", credential.UserName, credential.Password);
             byte[] authBytes = Encoding.UTF8.GetBytes(basicAuthValue);
             return Convert.ToBase64String(authBytes);
         }

src/shared/Microsoft.Git.CredentialManager/SecureStorage/ICredentialStore.cs renamed to src/shared/Microsoft.Git.CredentialManager/ICredentialStore.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license.
-namespace Microsoft.Git.CredentialManager.SecureStorage
+
+namespace Microsoft.Git.CredentialManager
 {
     /// <summary>
     /// Represents a secure storage location for <see cref="ICredential"/>s.