Update: Add library for Desktop Toast notifications

Based on sample code in:
https://github.com/WindowsNotifications/desktop-toasts

More info:
https://docs.microsoft.com/en-us/windows/uwp/design/shell/tiles-and-notifications/send-local-toast-desktop-cpp-wrl

Src/Update/DesktopToasts/DesktopNotificationManagerCompat.h

@@ -0,0 +1,108 @@
+// ******************************************************************
+// Copyright (c) Microsoft. All rights reserved.
+// This code is licensed under the MIT License (MIT).
+// THE CODE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH
+// THE CODE OR THE USE OR OTHER DEALINGS IN THE CODE.
+// ******************************************************************
+
+#pragma once
+#include <string>
+#include <memory>
+#include <Windows.h>
+#include <windows.ui.notifications.h>
+#include <wrl.h>
+#define TOAST_ACTIVATED_LAUNCH_ARG L"-ToastActivated"
+
+using namespace ABI::Windows::UI::Notifications;
+
+class DesktopNotificationHistoryCompat;
+
+namespace DesktopNotificationManagerCompat
+{
+    /// <summary>
+    /// If not running under the Desktop Bridge, you must call this method to register your AUMID with the Compat library and to
+    /// register your COM CLSID and EXE in LocalServer32 registry. Feel free to call this regardless, and we will no-op if running
+    /// under Desktop Bridge. Call this upon application startup, before calling any other APIs.
+    /// </summary>
+    /// <param name="aumid">An AUMID that uniquely identifies your application.</param>
+    /// <param name="clsid">The CLSID of your NotificationActivator class.</param>
+    HRESULT RegisterAumidAndComServer(const wchar_t *aumid, GUID clsid);
+
+    /// <summary>
+    /// Registers your module to handle COM activations. Call this upon application startup.
+    /// </summary>
+    HRESULT RegisterActivator();
+
+    /// <summary>
+    /// Creates a toast notifier. You must have called RegisterActivator first (and also RegisterAumidAndComServer if you're a classic Win32 app), or this will throw an exception.
+    /// </summary>
+    HRESULT CreateToastNotifier(IToastNotifier** notifier);
+
+    /// <summary>
+    /// Creates an XmlDocument initialized with the specified string. This is simply a convenience helper method.
+    /// </summary>
+    HRESULT CreateXmlDocumentFromString(const wchar_t *xmlString, ABI::Windows::Data::Xml::Dom::IXmlDocument** doc);
+
+    /// <summary>
+    /// Creates a toast notification. This is simply a convenience helper method.
+    /// </summary>
+    HRESULT CreateToastNotification(ABI::Windows::Data::Xml::Dom::IXmlDocument* content, IToastNotification** notification);
+
+    /// <summary>
+    /// Gets the DesktopNotificationHistoryCompat object. You must have called RegisterActivator first (and also RegisterAumidAndComServer if you're a classic Win32 app), or this will throw an exception.
+    /// </summary>
+    HRESULT get_History(std::unique_ptr<DesktopNotificationHistoryCompat>* history);
+
+    /// <summary>
+    /// Gets a boolean representing whether http images can be used within toasts. This is true if running under Desktop Bridge.
+    /// </summary>
+    bool CanUseHttpImages();
+}
+
+class DesktopNotificationHistoryCompat
+{
+public:
+
+    /// <summary>
+    /// Removes all notifications sent by this app from action center.
+    /// </summary>
+    HRESULT Clear();
+
+    /// <summary>
+    /// Gets all notifications sent by this app that are currently still in Action Center.
+    /// </summary>
+    HRESULT GetHistory(ABI::Windows::Foundation::Collections::IVectorView<ToastNotification*>** history);
+
+    /// <summary>
+    /// Removes an individual toast, with the specified tag label, from action center.
+    /// </summary>
+    /// <param name="tag">The tag label of the toast notification to be removed.</param>
+    HRESULT Remove(const wchar_t *tag);
+
+    /// <summary>
+    /// Removes a toast notification from the action using the notification's tag and group labels.
+    /// </summary>
+    /// <param name="tag">The tag label of the toast notification to be removed.</param>
+    /// <param name="group">The group label of the toast notification to be removed.</param>
+    HRESULT RemoveGroupedTag(const wchar_t *tag, const wchar_t *group);
+
+    /// <summary>
+    /// Removes a group of toast notifications, identified by the specified group label, from action center.
+    /// </summary>
+    /// <param name="group">The group label of the toast notifications to be removed.</param>
+    HRESULT RemoveGroup(const wchar_t *group);
+
+    /// <summary>
+    /// Do not call this. Instead, call DesktopNotificationManagerCompat.get_History() to obtain an instance.
+    /// </summary>
+    DesktopNotificationHistoryCompat(const wchar_t *aumid, Microsoft::WRL::ComPtr<IToastNotificationHistory> history);
+
+private:
+    std::wstring m_aumid;
+    Microsoft::WRL::ComPtr<IToastNotificationHistory> m_history = nullptr;
+};