Add encrypted file with plaintext footer and AES-CTR encryption #129

In apache/arrow#51669 it came up that Parquet C++ might not be handling properly the situation where an encrypted file has plaintext footer and is configured with AES-CTR encryption (the plaintext footer must be signed using AES-GCM regardless).

(with the caveat that issue description and its associated PRs look AI-generated)

It would be nice to have a file in parquet-testing with these characteristics, to exercise the read side of Parquet implementations.

cc @adamreeve @EnricoMi @ggershinsky