I think a option to chose specific relay list when publish/subscribe will be nice. Like:
```
client?.publish(event, Target.NIP65) // publish to nip65 relay list
client?.publish(event, Target.NIP17) // publish to nip17 relay list
client?.subscribe(event, Target.Custom(setOf...)) // publish to custom relay list
client?.subscribe(filter, Target.NIP65)
...
```
