Make RedisAsyncCommands.select() and auth() async

[ikkyuland]

Feature Request

Is your feature request related to a problem? Please describe

I have an issue when call RedisAsyncCommands.select(???) after .setAutoFlushCommands(false) , it will hang and timeout.

Describe the solution you'd like

I want RedisAsyncCommands.select(???) return RedisFuture (make it async like other method).

Describe alternatives you've considered

I may use RedisCommands (sync) and wrap by Future (FYI: I use lettuce in Scala).
A clear and concise description of any alternative solutions or features you've considered.

Teachability, Documentation, Adoption, Migration Strategy

This should benefit to user that use lettuce as pipeline