OS Detection and setting the old or new settings UI page accordingly (#2674)

* Added code to detect os build number

* To set the settings.exe according to the powerToys version that is running

* Modified the description of old UI for launcher and keyboard remapper

* Using API contracts instead of registry

* Removing file that was included by mistake

src/modules/keyboardmanager/dll/KeyboardManager.rc

@@ -5,7 +5,7 @@
 
 STRINGTABLE
 BEGIN
-    IDS_SETTINGS_DESCRIPTION                                     L"Customize your experience by remapping keys or creating new shortcuts!"
+    IDS_SETTINGS_DESCRIPTION                                     L"This feature requires Windows 10, May 2019 Update"
     IDS_KEYBOARDMANAGER                                         L"Keyboard Manager" 
 END
 

src/runner/pch.h

@@ -27,4 +27,5 @@
 #include <winrt/Windows.ApplicationModel.h>
 #include <winrt/Windows.Storage.h>
 
+#include <winrt/Windows.Foundation.Metadata.h>
 #include <wil/resource.h>

src/runner/settings_window.cpp

@@ -207,6 +207,41 @@ BOOL run_settings_non_elevated(LPCWSTR executable_path, LPWSTR executable_args,
     return process_created;
 }
 
+// The following three helper functions determine if the user has a build version higher than or equal to 19h1, as that is a requirement for xaml islands
+// Source : Microsoft-ui-xaml github
+// Link: https://github.com/microsoft/microsoft-ui-xaml/blob/c045cde57c5c754683d674634a0baccda34d58c4/dev/dll/SharedHelpers.cpp
+template<uint16_t APIVersion> bool IsAPIContractVxAvailable()
+{
+    static bool isAPIContractVxAvailableInitialized = false;
+    static bool isAPIContractVxAvailable = false;
+    if (!isAPIContractVxAvailableInitialized)
+    {
+        isAPIContractVxAvailableInitialized = true;
+        isAPIContractVxAvailable = winrt::Windows::Foundation::Metadata::ApiInformation::IsApiContractPresent(L"Windows.Foundation.UniversalApiContract", APIVersion);
+    }
+
+    return isAPIContractVxAvailable;
+}
+
+
+bool IsAPIContractV8Available()
+{
+    return IsAPIContractVxAvailable<8>();
+}
+
+bool Is19H1OrHigher()
+{
+    return IsAPIContractV8Available();
+}
+
+// This function returns true if the build is 19h1 or higher, so that we deploy the new settings.
+// It returns false otherwise.
+bool use_new_settings()
+{
+    return Is19H1OrHigher();
+}
+
+
 DWORD g_settings_process_id = 0;
 
 void run_settings_window()
@@ -223,7 +258,15 @@ void run_settings_window()
 
     // Arg 1: executable path.
     std::wstring executable_path = get_module_folderpath();
+
+    if (use_new_settings())
+    {
         executable_path.append(L"\\SettingsUIRunner\\Microsoft.PowerToys.Settings.UI.Runner.exe");
+    }
+    else
+    {
+        executable_path.append(L"\\PowerToysSettings.exe");
+    }
 
     // Arg 2: pipe server. Generate unique names for the pipes, if getting a UUID is possible.
     std::wstring powertoys_pipe_name(L"\\\\.\\pipe\\powertoys_runner_");