This minor change makes newBuilder() public to reduce verbosity for downstream.
To give you example, I am working on a parquet read / write into Arrow Record batch where the parquet data types are mapped to Arrow data types.
My Repo: https://github.com/mindhash/arrow-parquet-go
In such cases, it will be nice to have a builder API (newBuilder) be generic to accept a data type and return a respective array.
I am looking at a similar situation for JSON reader. I think this change will make the builder API much easier for upstream as well as internal packages.