TF-3924 Thread Detail Keep html view alive after thread load

lib/features/email/presentation/controller/single_email_controller.dart

@@ -221,6 +221,8 @@ class SingleEmailController extends BaseController with AppLoaderMixin {
 
   String get ownEmailAddress => mailboxDashBoardController.ownEmailAddress.value;
 
+  GlobalObjectKey? get htmlViewKey => _threadDetailController?.expandedEmailHtmlViewKey;
+
   SingleEmailController(
     this._getEmailContentInteractor,
     this._markAsEmailReadInteractor,

lib/features/email/presentation/email_view.dart

@@ -348,7 +348,7 @@ class EmailView extends GetWidget<SingleEmailController> {
                 return Padding(
                   padding: EmailViewStyles.emailContentPadding,
                   child: HtmlContentViewerOnWeb(
-                    key: ValueKey(tag),
+                    key: controller.htmlViewKey,
                     widthContent: bodyConstraints.maxWidth,
                     contentHtml: allEmailContents,
                     mailtoDelegate: controller.openMailToLink,

lib/features/thread_detail/presentation/thread_detail_controller.dart

@@ -143,6 +143,9 @@ class ThreadDetailController extends BaseController {
       networkConnectionController.isNetworkConnectionAvailable();
   bool get isThreadDetailEnabled =>
       threadDetailManager.isThreadDetailEnabled;
+  GlobalObjectKey? get expandedEmailHtmlViewKey => currentExpandedEmailId.value != null
+      ? GlobalObjectKey(currentExpandedEmailId.value!)
+      : null;
 
   @override
   void onInit() {