Log number of interactive sessions (#17682)

This sends a telemetry event if a session is interacted with.
Specifically, key events are essential to have an interactive session in
Windows Terminal, so we're tracking sessions that have had a key down
event.

(cherry picked from commit ac865e6666d16e436bd3df4f62697557990ce652)
Service-Card-Id: 93498660
Service-Version: 1.21

src/cascadia/WindowsTerminal/WindowThread.cpp

@@ -6,6 +6,8 @@
 
 using namespace winrt::Microsoft::Terminal::Remoting;
 
+bool WindowThread::_loggedInteraction = false;
+
 WindowThread::WindowThread(winrt::TerminalApp::AppLogic logic,
                            winrt::Microsoft::Terminal::Remoting::WindowRequestedArgs args,
                            winrt::Microsoft::Terminal::Remoting::WindowManager manager,
@@ -191,6 +193,16 @@ int WindowThread::_messagePump()
             break;
         }
 
+        if (!_loggedInteraction && (message.message == WM_KEYDOWN || message.message == WM_SYSKEYDOWN))
+        {
+            TraceLoggingWrite(
+                g_hWindowsTerminalProvider,
+                "SessionBecameInteractive",
+                TraceLoggingLevel(WINEVENT_LEVEL_VERBOSE),
+                TelemetryPrivacyDataTag(PDT_ProductAndServiceUsage));
+            _loggedInteraction = true;
+        }
+
         // GH#638 (Pressing F7 brings up both the history AND a caret browsing message)
         // The Xaml input stack doesn't allow an application to suppress the "caret browsing"
         // dialog experience triggered when you press F7. Official recommendation from the Xaml

src/cascadia/WindowsTerminal/WindowThread.h

@@ -42,6 +42,7 @@ private:
     winrt::event_token _UpdateSettingsRequestedToken;
 
     std::unique_ptr<::IslandWindow> _warmWindow{ nullptr };
+    static bool _loggedInteraction;
 
     int _messagePump();
     void _pumpRemainingXamlMessages();