fix parser issues with empty template vars, make matching more relaxed

engine-cli/src/test/resources/scripts/script_to_interpolate.js

@@ -1,3 +1,19 @@
-let foo=TEMPLATE(parameter1:value1);
+/*
+ * Copyright (c) 2022 nosqlbench
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+let foo=TEMPLATE(parameter1,value1);
 let bar=TEMPLATE(parameter2);
 let baz;