Support same message pattern format as nestjs client module

[Stene3]

Hi,
first of all let me thank you for this great library.

I am not sure if this is a bug or feature request, but I would expect this plugin to work like a drop in replacement for built in nestjs transport module, so I have classified this as a bug:

Nestjs supports multiple formats for MessagePattern. It can be object like { cmd: "sum" }, or a string pattern similarly to EventPatterns order.sum. While this works with builtin TCP or NATS transports, it does not with the JetStream transport from this repository.

Are you aware of it, was it intentional or you have never ever used string patterns so you could never know about that?

Thanks for the answer.