Add --launch= command line argument to start game executables

`--launch=` option accepts both executable paths and URIs for launcher
compatibility.

Some games like Sackboy or Telltale Expanse Series on Epic
will fail to launch correctly if .exe path is used directly. Instead they
require proper launcher URI.

This change will allow UEVR fronted to act as a launcher for games.

Example. Creating shortcut to:
```
UEVRInjector.exe "--launch=com.epicgames.launcher://apps/da36711940d4460da57d8d6ad67236a4%3Aa1afcdb1d2344232954be97d4b86b9a8%3Acfbbc006f3ee4ba0bfff3ffa46942f90?action=launch&silent=true" --attach=CosmicShake-Win64-Shipping
```

Will allow to automatically launch and inject Sponge Bob: Cosmic Shake on EGS

UEVR/MainWindow.xaml.cs

@@ -172,6 +172,7 @@ public partial class MainWindow : Window {
 
         private ExecutableFilter m_executableFilter = new ExecutableFilter();
         private string? m_commandLineAttachExe = null;
+        private string? m_commandLineLaunchExe = null;
         private bool m_ignoreFutureVDWarnings = false;
 
         [System.Runtime.InteropServices.DllImport("user32.dll")]
@@ -187,6 +188,11 @@ public MainWindow() {
             foreach (string arg in args) {
                 if (arg.StartsWith("--attach=")) {
                     m_commandLineAttachExe = arg.Split('=')[1];
+                    continue;
+                }
+                if (arg.StartsWith("--launch=")) {
+                    m_commandLineLaunchExe = arg.Substring(arg.IndexOf('=') + 1); // game exe URI may contain any characters including '='
+                    continue;
                 }
             }
         }
@@ -251,6 +257,7 @@ private void RestartAsAdminButton_Click(object sender, RoutedEventArgs e) {
         }
 
         private DateTime m_lastAutoInjectTime = DateTime.MinValue;
+        private bool m_launchExeDone = false;
 
         private void Update_InjectStatus() {
             if (m_connected) {
@@ -261,6 +268,21 @@ private void Update_InjectStatus() {
             DateTime now = DateTime.Now;
             TimeSpan oneSecond = TimeSpan.FromSeconds(1);
 
+            if (m_commandLineLaunchExe != null && !m_launchExeDone) {
+                try {
+                    Process.Start(new ProcessStartInfo {
+                        FileName = m_commandLineLaunchExe,
+                        UseShellExecute = true // for launcher compatiblity, executable might be an URI
+                    });
+
+                    m_launchExeDone = true;
+                }
+                catch (Exception) {
+                    MessageBox.Show("Failed to launch: " + m_commandLineLaunchExe, "Launch error", MessageBoxButton.OK, MessageBoxImage.Error);
+                    Application.Current.Dispatcher.Invoke(new Action(() => { Application.Current.Shutdown(1); }));
+                }
+            }
+
             if (m_commandLineAttachExe == null) {
                 if (m_lastSelectedProcessId == 0) {
                     m_injectButton.Content = "Inject";