Change the AnnotationLayer.prototype.getEditableAnnotations method to return an iterator

This method is only used with loops, and it should be a tiny bit more efficient to use an iterator directly rather than first iterating through the underlying `Map` to create a temporary `Array` that we finally iterate through at the call-site.

src/display/annotation_layer.js

@@ -4100,7 +4100,7 @@ class AnnotationLayer {
   }
 
   getEditableAnnotations() {
-    return Array.from(this.#editableAnnotations.values());
+    return this.#editableAnnotations.values();
   }
 
   getEditableAnnotation(id) {

src/display/editor/annotation_editor_layer.js

@@ -416,8 +416,7 @@ class AnnotationEditorLayer {
       }
 
       // Show the annotations that were hidden in enable().
-      const editables = annotationLayer.getEditableAnnotations();
-      for (const editable of editables) {
+      for (const editable of annotationLayer.getEditableAnnotations()) {
         const { id } = editable.data;
         if (this.#uiManager.isDeletedAnnotationElement(id)) {
           editable.updateEdited({ deleted: true });