Revert "Code refactoring (nod-ai#1817)"

This reverts commit c61b6f8.

shark/iree_utils/vulkan_target_env_utils.py

@@ -57,7 +57,11 @@ def get_version(triple):
 @functools.cache
 def get_extensions(triple):
     def make_ext_list(ext_list):
-        return ", ".join(ext_list)
+        res = ""
+        for e in ext_list:
+            res += e + ", "
+        res = f"[{res[:-2]}]"
+        return res
 
     arch, product, os = triple
     if arch == "m1":