Support NKey authentication when connecting to a NATS instance

[gap2709]

What motivated this proposal?

Our editor has made an update of its nats product by adding a NKey authentication.
Before to get nats reports, we used the command below
nats stream report
Now we have to type
nats --nkey path/to/nkey_file stream report
where nkey file contains the key used for authentication

What is the proposed change?

I would like the possibility to permit use of the nkey while connecting to the nats cluster from the bridge, because when starting it, I have the error below
2024/04/25 17:36:24.441801 [ERR] error starting bridge, nats: Authorization Violation

Who benefits from this change?

It is especially my team, we have to incercept nats event in order to publish them in a output topic.

What alternatives have you evaluated?

I have no idea