Update on "[executorch][core] NamedDataMap interface"

Add NamedDataMap interface to runtime.

Differential Revision: [D66834552](https://our.internmc.facebook.com/intern/diff/D66834552/)

[ghstack-poisoned]

Author: lucylq

runtime/core/named_data_map.h

@@ -42,6 +42,18 @@ class ET_EXPERIMENTAL NamedDataMap {
   ET_NODISCARD virtual Result<FreeableBuffer> get_data(
       const char* fqn) const = 0;
 
+  /**
+   * Loads data corresponding to the fqn into the provided buffer.
+   *
+   * @param fqn Fully qualified name of the tensor.
+   * @param size The number of bytes to load.
+   * @param buffer The buffer to load the data into. Must point to at least
+   * `size` bytes of memory.
+   * @return An error code on if the load was successful.
+   */
+  ET_NODISCARD virtual Error
+  load_data_into(const char* fqn, size_t size, void* buffer);
+
   /**
    * Get the number of keys in the NamedDataMap.
    *