Remove JetStream consume / fetch default batch

[mtmk]

Proposed change

Overload + config ctor:

consume/fetch(int batch)
consume/fetch(new Config(int batch))

This would eliminate errors like setting consumer batch size less than 1000 then having issues consuming.

[Jarema]

I think that consume should have built in default batch value (but configurable). For fetch I agree that there should be no default value.

[mtmk]

I think that consume should have built in default batch value (but configurable).

what would be a sensible default? Currently it's 1000