Incorporate files_external and auth changes from customer demo

[AndyScherzinger]

$subject

TBD for Nextcloud 22 and up

Delivery Date

End of September / Beginning of October (no fixed date, to be aligned with Fabian)

[joshtrichards]

I'm guessing this was long ago addressed, probably in #29349 (and maybe also #29484 but unsure if related).

Closable Issue?

[AndyScherzinger]

Thanks for the ping, @blizzz what do you think?

[blizzz]

ack