feature-request Support specifying TrueNAS app train

[SimJoSt]

The Nextcloud app in TrueNAS is available in different trains.
The app from the "stable" train is more simple, whereas the one from the "community" train is more feature complete (notify push support, etc.), which is great of ease of use, something that HexOS strives for.

Currently, I don't know of a way to specify a train in app install scripts.
It would be great to be able to do that, so we could also support "Nextcloud (community train)".