Update on "Export lora weights to sep file"

Differential Revision: [D83777195](https://our.internmc.facebook.com/intern/diff/D83777195/)

[ghstack-poisoned]

Author: lucylq

extension/named_data_map/test/merged_data_map_test.cpp

@@ -23,7 +23,7 @@
 using namespace ::testing;
 using executorch::extension::FileDataLoader;
 using executorch::extension::FlatTensorDataMap;
-using executorch::extension::MergedDataMap;
+using executorch::extension::merged_data_map::MergedDataMap;
 using executorch::runtime::DataLoader;
 using executorch::runtime::Error;
 using executorch::runtime::NamedDataMap;