List subjects for all the messages stored in NATS Stream (Jet Stream).
Lets say if we have 100 Messages in the Jet Stream under two subjects S1.S2.S3 & S1.S4.
Some thing like SELECT DISTINCT Subjects FROM Stream where No.of.Messages > 0
should yield: S1.S2.S3, S1.S4
This only for debugging/troubleshooting only.