js: make js.Subscribe context aware

[wallyqs]

Can now attach a context to a subscription so that it is unsubscribed and/or consumer deleted via propagation of cancellation via parent context. This helps specially with kv.Watch functions that have an ordered consumer subscription.

Signed-off-by: Waldemar Quevedo wally@synadia.com

[coveralls]

Coverage increased (+0.3%) to 85.156% when pulling 16d26f8 on js-subscribe-ctx into d7c1d78 on main.

[ripienaar]

Nice, I am not that concerned to make this work for kv atm though your change is small enough there.

For kv we must not accept WatchOpts on various places where its accepted now - we need to add a new kind of opt like CancelOpt that only accepts nats.Context() since that the only valid option for Keys() for example. I can take care of that once the basic cancelable subscribe and order consumer is in place

[kozlovic]

LGTM

[tpihl]

Will this work as a cancel more messages or will it delete a durable subscriber created in the subscribe call with WithDurable?

[wallyqs]

If the app auto-created the durable (that is, without using AddConsumer) then the durable subscriber will be deleted when the context is canceled as well.