Followup task to #7111, which adds support for writing encrypted Parquet files.

The Parquet format allows encrypting some or all column data while keeping footers in plaintext for compatibility with readers that don't support encryption. See spec.

Arrow-rs already supports reading plaintext footers, it will support writing encrypted parquet files once #7111 is merged and should also support writing parquet files with plaintext footers. See here to start.