Simplify observed values about text selection in composer

hasTextSelection had no interest.

The other two values have been put inside an object to observe only one object.

lib/features/composer/presentation/composer_view_web.dart

@@ -963,9 +963,11 @@ class ComposerView extends GetWidget<ComposerController> {
     }
 
     return Obx(() {
-      if (controller.hasTextSelection.value &&
-          controller.textSelectionCoordinates.value != null) {
-        final coordinates = controller.textSelectionCoordinates.value!;
+      final textSelection = controller.editorTextSelection.value;
+      if (textSelection != null &&
+          textSelection.hasSelection &&
+          textSelection.coordinates != null) {
+        final coordinates = textSelection.coordinates!;
         return PositionedDirectional(
           start: coordinates.dx,
           top: coordinates.dy,