import from_blob from executorch::extension

Summary: this diff import `from_blob` from `executorch::extension` namespace to in line with recent namespace updates.

Reviewed By: dbort, dvorjackz

Differential Revision: D64022153

fbshipit-source-id: 42a8cba91b10150fd78ce041b7cc9b35c42ec887

Author: Gasoonjia

docs/source/llm/getting-started.md

@@ -210,6 +210,7 @@ Create a file called main.cpp with the following contents:
 
 using exec_aten::ScalarType;
 using exec_aten::Tensor;
+using executorch::extension::from_blob;
 using executorch::extension::Module;
 using executorch::runtime::EValue;
 using executorch::runtime::Result;

examples/llm_manual/main.cpp

@@ -19,6 +19,7 @@
 
 using exec_aten::ScalarType;
 using exec_aten::Tensor;
+using executorch::extension::from_blob;
 using executorch::extension::Module;
 using executorch::runtime::EValue;
 using executorch::runtime::Result;