Update on "Introduce public MergedDataMap"

Add public merged data map. Module can use this to resolve multiple named data maps.

Differential Revision: [D83527299](https://our.internmc.facebook.com/intern/diff/D83527299/)

[ghstack-poisoned]

Author: lucylq

extension/named_data_map/test/CMakeLists.txt

@@ -19,7 +19,7 @@ endif()
 include(${EXECUTORCH_ROOT}/tools/cmake/Test.cmake)
 
 add_custom_command(
-  OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/ModuleAddMulProgram.pte"
+  OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/ModuleAddMulProgram.ptd"
          "${CMAKE_CURRENT_BINARY_DIR}/ModuleAddMulProgram.pte"
          "${CMAKE_CURRENT_BINARY_DIR}/ModuleLinearProgram.ptd"
          "${CMAKE_CURRENT_BINARY_DIR}/ModuleLinearProgram.pte"