CMake: Write target architecture into module info files

Store the target architecture in the module information files under the
key 'built_with.architecture'.

Task-number: QTBUG-111158
Change-Id: Ida4cde3b15103773824a8d9d78f082540b806736
Reviewed-by: Amir Masoud Abdol <amir.abdol@qt.io>
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

cmake/ModuleDescription.json.in

@@ -7,6 +7,7 @@
         "compiler_target": "${CMAKE_CXX_COMPILER_TARGET}",
         "compiler_version": "${CMAKE_CXX_COMPILER_VERSION}",
         "cross_compiled": ${cross_compilation},
-        "target_system": "${CMAKE_SYSTEM_NAME}"
+        "target_system": "${CMAKE_SYSTEM_NAME}",
+        "architecture": "${TEST_architecture_arch}"
     }
 }