Fixes #1544 - Remove media upload dialog share button

ElementX/Sources/Screens/MediaUploadPreviewScreen/View/MediaUploadPreviewScreen.swift

@@ -59,7 +59,7 @@ private struct PreviewView: UIViewControllerRepresentable {
     let title: String?
 
     func makeUIViewController(context: Context) -> UIViewController {
-        let previewController = QLPreviewController()
+        let previewController = PreviewViewController()
         previewController.dataSource = context.coordinator
         previewController.delegate = context.coordinator
         
@@ -123,3 +123,11 @@ struct MediaUploadPreviewScreen_Previews: PreviewProvider {
         MediaUploadPreviewScreen(context: viewModel.context)
     }
 }
+
+private class PreviewViewController: QLPreviewController {
+    override func viewWillLayoutSubviews() {
+        super.viewWillLayoutSubviews()
+        
+        navigationItem.rightBarButtonItem = nil
+    }
+}