Add overlay and block app list during install/uninstall (#3385)

* Implement app installation progress overlay and refactor progress bar handling

* Add overlay background color settings and ensure minimum progress bar value

* Add busy overlay functionality and progress bar updates for installation process

* Refactor busy overlay implementation to dynamically adjust size based on app area dimensions

functions/private/Show-WPFInstallAppBusy.ps1

@@ -0,0 +1,21 @@
+function Show-WPFInstallAppBusy {
+    <#
+    .SYNOPSIS
+        Displays a busy overlay in the install app area of the WPF form.
+        This is used to indicate that an install or uninstall is in progress.
+        Dynamically updates the size of the overlay based on the app area on each invocation.
+    .PARAMETER text
+        The text to display in the busy overlay. Defaults to "Installing apps...".
+    #>
+    param (
+        $text = "Installing apps..."
+    )
+    $sync.form.Dispatcher.Invoke([action]{
+        $sync.InstallAppAreaOverlay.Visibility = [Windows.Visibility]::Visible
+        $sync.InstallAppAreaOverlay.Width = $($sync.InstallAppAreaScrollViewer.ActualWidth * 0.4)
+        $sync.InstallAppAreaOverlay.Height = $($sync.InstallAppAreaScrollViewer.ActualWidth * 0.4)
+        $sync.InstallAppAreaOverlayText.Text = $text
+        $sync.InstallAppAreaBorder.IsEnabled = $false
+        $sync.InstallAppAreaScrollViewer.Effect.Radius = 5
+        })
+    }