Add --delay option to wait before injection

Some games don't respond well to be injected directly on boot.
Intro movies, menus, loading screens can appear broken or as a black
screen.

This commit augments `--attach` mode with `--delay` parameter allowing
UEVR injector to wait upon detecting target application. This gives user
time to get into the game without needing to go back to the injector UI
and pressing inject manually.

Example: `UEVRInjector.exe --attach=CosmicShake-Win64-Shipping --delay=30`
will wait for SpongeBob Cosmic Shake process to spawn, then wait 30s on
top and inject.

UEVR/MainWindow.xaml.cs

@@ -173,6 +173,7 @@ public partial class MainWindow : Window {
         private ExecutableFilter m_executableFilter = new ExecutableFilter();
         private string? m_commandLineAttachExe = null;
         private string? m_commandLineLaunchExe = null;
+        private int m_commandLineDelayInjection = 0;
         private bool m_ignoreFutureVDWarnings = false;
 
         [System.Runtime.InteropServices.DllImport("user32.dll")]
@@ -194,6 +195,16 @@ public MainWindow() {
                     m_commandLineLaunchExe = arg.Substring(arg.IndexOf('=') + 1); // game exe URI may contain any characters including '='
                     continue;
                 }
+                if (arg.StartsWith("--delay=")) {
+                    try {
+                        m_commandLineDelayInjection = int.Parse(arg.Split('=')[1]);
+                    }
+                    catch {
+                        m_commandLineDelayInjection = 0;
+                    }
+
+                    continue;
+                }
             }
         }
 
@@ -258,6 +269,7 @@ private void RestartAsAdminButton_Click(object sender, RoutedEventArgs e) {
 
         private DateTime m_lastAutoInjectTime = DateTime.MinValue;
         private bool m_launchExeDone = false;
+        private int? m_delayInjectionTimer = null;
 
         private void Update_InjectStatus() {
             if (m_connected) {
@@ -335,6 +347,16 @@ private void Update_InjectStatus() {
                     return;
                 }
 
+                if (m_commandLineDelayInjection > 0) {
+                    if (m_delayInjectionTimer == null) {
+                        m_delayInjectionTimer = m_commandLineDelayInjection;
+                    }
+
+                    m_injectButton.Content = m_commandLineAttachExe.ToLower() + " found. Delaying " + m_delayInjectionTimer + "s";
+                    m_delayInjectionTimer--;
+                    if (m_delayInjectionTimer > 0) return;
+                }
+
                 if (now - m_lastAutoInjectTime > oneSecond) {
                     if (m_nullifyVRPluginsCheckbox.IsChecked == true) {
                         IntPtr nullifierBase;
@@ -377,6 +399,8 @@ private void Update_InjectStatus() {
 
                     m_lastAutoInjectTime = now;
                     m_commandLineAttachExe = null; // no need anymore.
+                    m_delayInjectionTimer = null;
+                    m_commandLineDelayInjection = 0;
                     FillProcessList();
                     if (m_focusGameOnInjectionCheckbox.IsChecked == true)
                     {