feat: allow to use WindowHandlingModifier outside of RCTMainWindow

Author: okwasniewski

packages/react-native/Libraries/SwiftExtensions/RCTMainWindow.swift

@@ -37,15 +37,17 @@ public struct RCTMainWindow: Scene {
 /**
  Handles data sharing between React Native and SwiftUI views.
  */
-struct WindowHandlingModifier: ViewModifier {
+public struct WindowHandlingModifier: ViewModifier {
   typealias UserInfoType = Dictionary<String, AnyHashable>
 
   @Environment(\.reactContext) private var reactContext
   @Environment(\.openWindow) private var openWindow
   @Environment(\.dismissWindow) private var dismissWindow
   @Environment(\.supportsMultipleWindows) private var supportsMultipleWindows
 
-  func body(content: Content) -> some View {
+  public init() {}
+  
+  public func body(content: Content) -> some View {
     // Attach listeners only if app supports multiple windows
     if supportsMultipleWindows {
       content