Fix asset list not stopping read job when clearing

Operators may want to refresh the visible list of assets (e.g. when an asset is
added), which wouldn't work correctly when the asset list was already loading
in a background thread.

Part of the brush assets project, see:
- https://projects.blender.org/blender/blender/issues/116337
- https://projects.blender.org/blender/blender/pulls/106303

source/blender/editors/asset/intern/asset_list.cc

@@ -272,6 +272,7 @@ void AssetList::clear(const bContext *C)
   filelist_readjob_stop(files, CTX_wm_manager(C));
   filelist_freelib(files);
   filelist_clear(files);
+  filelist_tag_force_reset(files);
 
   WM_main_add_notifier(NC_ASSET | ND_ASSET_LIST, nullptr);
 }