This commit improves Redis configuration by introducing `@SpringSessionRedisConnectionFactory` qualifier for explicitly declaring a `RedisConnectionFactory` to be used by Spring Session. This is in particular useful in scenarios with multiple `RedisConnectionFactory` beans present in the application context.
Redis configuration is simplified and no longer registers a Spring Session specific `RedisOperations<Object,Object>` bean with the application context.
Users are however able to obtain `RedisOperations<Object,Object>` instance used by Spring Session using newly introduced `@SpringSessionRedisOperations` annotation.
