Change logic of changelog/update notifier

[jospoortvliet]

When users upgrade to 17.0.0, they will see what's new in Nextcloud 17 thanks to the changelog server.

Unfortunately, if they upgrade from 16.0.3 to 17.0.2, they will not see what is new in 17. They might see what is new in 17.0.2 compared to 17.0.1, but that's far less interesting and relevant.

We could try to be super smart about this, but, as minor releases tend to not be so interesting for normal users, the best solution is probably to simply show the changelog of a major release once per user. So forget about minor releases, what matters is: if you move to a new major release (irrespective of the minor release you go to), show the changelog of that major release.

This has the side benefit of being more realistic with regards to how we keep the changelog server up-to-date (mostly on major releases)...

@blizzz Ack?

[rullzer]

Early adopters should be rewarded. If you don't upgrade to the beta you don't truly love us 😢
But you are right that we should detect this. So that if you skipped 17.0.0 and went directly to 17.0.1 or 17.0.2 we can automatically submit your instance to the hall of shameful late adopters 😉

[blizzz]

we can automatically submit your instance to the hall of shameful late adopters

with the addendum "you should switch to Arch, btw".

[blizzz]

I guess that's not relevant anymore with 29?

[jospoortvliet]

I guess that's not relevant anymore with 29?

I'm not sure if this is the case, the new popup is for end users in the UI, not for admins...