Motivation:

When `RedisConnection.allowSubscriptions` is set to `false`, the connection could still be in a subscription state
leaving further commands to fail slowly from a full roundtrip to Redis, rather than succeeding as expected.

This changes the implementation so that it triggers a full unsubscribe from patterns and channels when set to `false`.

Modifications:

- Change: `RedisConnection.allowSubscriptions` to call `unsubscribe()` and `punsubscribe()` when set to `false`
- Change: `RedisPubSubHandler` to prefix storage of all dictionary keys to avoid name clashes between pattern and channel subscriptions

Result:

Developers should now have more deterministic and unsurprising behavior with PubSub
in regards to subscription management and connection state.