Add validation for name length to be under 37 characters in 'az network application-gateway private-link add'

Author: koudaiii

src/azure-cli/azure/cli/command_modules/network/aaz/latest/network/application_gateway/private_link/_add.py

@@ -133,7 +133,9 @@ def _execute_operations(self):
 
     @register_callback
     def pre_operations(self):
-        pass
+        name = self.ctx.args.name
+        if has_value(name) and len(name.to_serialized_data()) > 37:
+            raise ValueError("Name exceeds the maximum character limit of 37.")
 
     @register_callback
     def post_operations(self):