Fix updating a non unique consumer on workqueue stream not returning an error

[mdawar]

This is a possible fix for #4653.

Changes made:

1. Added tests for creating and updating consumers on a work queue stream with overlapping subjects.
2. Check for overlapping subjects before updating the consumer config.
3. Changed func (*stream).partitionUnique(partitions []string) bool to accept the consumer name being checked so we can skip it while checking for overlapping subjects (Required for FilterSubjects updates), wasn't needed before because the checks were made on creation only.

There's only 1 thing that I'm not sure about.

In the current work queue stream conflict checks, the consumer config Direct is being checked if false, should we also make this check before the update?

Signed-off-by: Pierre Mdawar pierre@mdawar.dev

[derekcollison]

LGTM! Thanks for the contribution as always.