Add array_concat_agg function for BigQuery compatibility

Why it matters

This feature introduces the array_concat_agg aggregate function to improve interoperability with BigQuery by offering a familiar function name that behaves identically to groupArrayArray. It helps users migrating queries or integrating systems that rely on BigQuery's syntax, simplifying the transition and usage.

How to use it

Use the array_concat_agg aggregate function in your SELECT queries just like any other aggregate function. Since it is an alias of groupArrayArray, no additional setup or configuration is required. Example usage:

SELECT array_concat_agg(column_name) FROM table_name;