[RedisIO] - it's not possible to retrieve with PFCOUNT command the count of all the unique queries

Currently, it's not possible to use PFCOUNT command to retrieve the unique queries

it seems that what we need to do is to create a public function on Read that would do it something like:

``
```

public Response readUsingPFCOUNTCommand(String key) {

return pipeline.pfcount(key, value);

}
```

``

Imported from Jira [BEAM-13326](https://issues.apache.org/jira/browse/BEAM-13326). Original Jira may contain additional context.
Reported by: robertosf90.

Start in the RedisIO Read API and inspect how Redis commands are exposed, focusing on the requested PFCOUNT operation and the proposed readUsingPFCOUNTCommand entry point. Done means the public Read API can retrieve the count of unique queries with PFCOUNT and has coverage for that behavior.

Written by the indexing model from the issue text.