Support configuration editing of "object" and "kv" stores

[timo102]

Proposed change

The edit configuration functionality is very useful. Stream and consumer configuration editing is fully supported by the command line tool. The same functionality would be good to have for the object store and the key-value store.

Use case

Changing the replica number in an already deployed instance without losing the content of the object store or key-value store.

Contribution

No response

[ripienaar]

For KV this was recently contributed in #1240

Would be great to get a similar contribution for object store. Both nats.go APIs only got edit ability recently.