feat(login): add origin check at login

[Altahrim]

Summary

Check Origin header on login page

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[inet-cologne]

@Altahrim, @skjnldsv, @sorbaugh, @artonge , @canadaduane
Hey guys,
may it be that the change made here in #49560 produces somehow login problems within Nextcloud files app, Nextcloud Talk app and perhaps causing issues with Calendar subscription synchronising?
Since a couple of days after updating (several instances!!) Nextcloud Server to 30.0.5, problems were occurring that Login fails. These could be fixed by deleting and reinstalling and reconfiguring the apps.
30.0.6 does not fix the situation either but now even reinstallation does not help anymore. Login with the above mentioned iOS apps are not possible any more!!
Please see issue #50619!

Thanks for checking that!!
Chris

[susnux]

@inet-cologne this is not included in Nextcloud 30 but only Nextcloud 31.