Fix #119384: Outliner crash extend mode toggle on objects sharing data

This builds upon 8e060b44da

Above commit also checked shared data against the **active** object,
however objects not being active can also share data with other objects
in multi-object-editing. This is now checked, so the shared icon is used
for them as well as disabeling "extend" (same as in 8e060b44da).

Noticed other issues with this feature:
- extending should only show in the tooltip for pose and editmode
(`outliner_item_mode_toggle` ignores other modes for extending)
- removing a particular item (if it is not the active) from a mode does
not work well/at all.
- these will be addressed separately though

@@ -2145,0 +2146,4 @@
+                                                    Object *ob,
+                                                    Object *ob_active)
+{
+  bool object_data_shared = (ob->data == ob_active->data);

@@ -2145,0 +2149,4 @@
+  bool object_data_shared = (ob->data == ob_active->data);
+  /* If the ID has multiple users, also check if any object using it is in the same mode as the
+   * active object. */
+  if (static_cast<const ID *>(ob->data)->us > 1) {

@@ -2145,0 +2155,4 @@
+    Vector<Object *> objects_in_mode = BKE_view_layer_array_from_objects_in_mode_params(
+        tvc->scene, tvc->view_layer, nullptr, &params);
+    for (Object *object : objects_in_mode) {
+      object_data_shared |= object->data == ob->data;

@@ -2142,6 +2142,26 @@ static void outliner_buttons(const bContext *C,
   }
 }
 
+static bool outliner_mode_toggle_object_data_shared(TreeViewContext *tvc,

@@ -2144,1 +2144,4 @@
 
+static bool outliner_mode_toggle_object_data_shared(TreeViewContext *tvc,
+                                                    Object *ob,
+                                                    Object *ob_active)

@@ -2145,0 +2146,4 @@
+                                                    Object *ob,
+                                                    Object *ob_active)
+{
+  bool object_data_shared = (ob->data == ob_active->data);

@@ -2145,0 +2152,4 @@
+  if (static_cast<const ID *>(ob->data)->us > 1) {
+    ObjectsInModeParams params = {0};
+    params.object_mode = ob_active->mode;
+    Vector<Object *> objects_in_mode = BKE_view_layer_array_from_objects_in_mode_params(

@@ -2145,0 +2154,4 @@
+    params.object_mode = ob_active->mode;
+    Vector<Object *> objects_in_mode = BKE_view_layer_array_from_objects_in_mode_params(
+        tvc->scene, tvc->view_layer, nullptr, &params);
+    for (Object *object : objects_in_mode) {