Fix #112985: Outliner header context menu shows asset operators

The Outliner exposed its context to the header as well which makes some
operators available there. While technically this is all fine, it's a
bit odd to the user, since they don't expect data-editing operations
when right clicking on a header that itself doesn't list data. Instead
only expose the Outliner context in the main region.

source/blender/editors/space_outliner/outliner_context.cc

@@ -35,9 +35,9 @@ static const char *outliner_context_dir[] = {
     nullptr,
 };
 
-int /*eContextResult*/ outliner_context(const bContext *C,
-                                        const char *member,
-                                        bContextDataResult *result)
+int /*eContextResult*/ outliner_main_region_context(const bContext *C,
+                                                    const char *member,
+                                                    bContextDataResult *result)
 {
   SpaceOutliner *space_outliner = CTX_wm_space_outliner(C);
 

source/blender/editors/space_outliner/outliner_intern.hh

@@ -674,7 +674,9 @@ void outliner_sync_selection(const bContext *C, SpaceOutliner *space_outliner);
 
 /* `outliner_context.cc` */
 
-int outliner_context(const bContext *C, const char *member, bContextDataResult *result);
+int outliner_main_region_context(const bContext *C,
+                                 const char *member,
+                                 bContextDataResult *result);
 
 /**
  * Helper to safely "cast" a #TreeElement to its new C++ #AbstractTreeElement, if possible.

source/blender/editors/space_outliner/space_outliner.cc

@@ -618,7 +618,6 @@ void ED_spacetype_outliner()
   st->id_remap = outliner_id_remap;
   st->foreach_id = outliner_foreach_id;
   st->deactivate = outliner_deactivate;
-  st->context = outliner_context;
   st->blend_read_data = outliner_space_blend_read_data;
   st->blend_read_after_liblink = outliner_space_blend_read_after_liblink;
   st->blend_write = outliner_space_blend_write;
@@ -633,6 +632,7 @@ void ED_spacetype_outliner()
   art->free = outliner_main_region_free;
   art->listener = outliner_main_region_listener;
   art->message_subscribe = outliner_main_region_message_subscribe;
+  art->context = outliner_main_region_context;
   BLI_addhead(&st->regiontypes, art);
 
   /* regions: header */