add cron status badge to admin setting

[Grotax]

Summary

Display a info card in the settings, indicating when the last news update job ran.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Changelog entry added for all important changes.

[Grotax]

It's just a first draft. I haven't tested yet if the logic works.
Info would only refresh on page reload, but I think that is enough.
And I think this would help admins to debug issues.

In theory a button to unlock a stuck job would be possible.

[Grotax]

This feature will only be available in Nextcloud 26+, everything below will disable the box.

[Grotax]

This is tested now and works like a charm, the formular is of course debatable.

return Date.now() / 1000 - this.lastCron > parseInt(this.updateInterval) * 2

Since the smaller the update interval gets the less likely it is that news will actually finish it's run in time.
Maybe we could add a +x that makes sure that we have at least 30, 15 min.

[Grotax]

I will merge this :)