Fix: Missing node asset menu updates after mark asset

Use of node group assets relies on a few properties written to asset
meta-data for proper filtering of assets in menus (add modifier menu,
node add menu, 3D view menus for tools). Currently these meta-data
properties are written when updating their source properties and when
saving the file. That means they *aren't* written when marking a group
as an asset, which is necessary because the meta-data doesn't exist
before when the group isn't an asset. Currently users have to save the
file to update menus in this case, which isn't intuitive.

As a fix, call the function to write the meta-data when marking a
data-block as an asset.

@@ -26,6 +26,7 @@ struct IDProperty;
 struct PreviewImage;
 
 typedef void (*PreSaveFn)(void *asset_ptr, struct AssetMetaData *asset_data);
+typedef void (*MarkAssetFn)(void *asset_ptr, struct AssetMetaData *asset_data);

@@ -1127,10 +1127,16 @@ static void node_tree_asset_pre_save(void *asset_ptr, AssetMetaData * /*asset_da
   node_update_asset_metadata(*static_cast<bNodeTree *>(asset_ptr));
 }
 
+static void node_tree_asset_mark_asset(void *asset_ptr, AssetMetaData * /*asset_data*/)