[Feature Request]: RedisIO support pcollection of <byte[], byte[]> in addition to the <String, String> api

### What would you like to happen?

Add new API in RedisIO to support currently the api supports only Strings.
In case we would like to save to redis encoded Avro messages and decode it when reading there is a failure.
The problem is that casting or creating new string out of the avro byte array adds headers which cannot be decoded easily when reading..

currently in our implementation we wrote a custom Redis connector that does that. we will be happy to contribute the code.
either by adding new connector or adding new APIs to current connector

### Issue Priority

Priority: 2 (default / most feature requests should be filed as P2)

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