Allow custom temporary NATS subjects detection

[AlixBa]

In order to avoid this, as both _INBOX and _R_ are used for temporary request/reply subjects.

It can also be useful for internal operations. On my side I use custom subjects for warming up my application, _TEMP.warmup.UUID. They pop-up in the span names and as I use a UUID I'd like to rename these ones to (temporary) too.