feat(awslambda): add new check awslambda_function_vpc_multi_az (#4816)

Co-authored-by: Sergio <sergio@prowler.com>

tests/providers/aws/services/awslambda/awslambda_service_test.py

@@ -221,6 +221,7 @@ class Test_Lambda_Service:
                 lambda_arn_1
             ].url_config.cors_config.allow_origins == ["*"]
             assert awslambda.functions[lambda_arn_1].vpc_id == "vpc-123abc"
+            assert awslambda.functions[lambda_arn_1].subnet_ids == {"subnet-123abc"}
 
             assert awslambda.functions[lambda_arn_1].tags == [{"test": "test"}]