Add process for external page content verification

[dkehne]

Motivation

Various actors in municipal integration work should be able and willing to collect information and prepare it in Integreat in a way that is appropriate for the target group.

Proposed Solution

Verwalter can assign an organiziation to a page. this organization could be notified by email and get a links with an session-id to change the german text (for 24h/48h) or mark it as up to date. this process of verfication/change-requests by e.g. email can be automated every 6 month/12 month. If organizations wish to have permanent access they could get a user account with page-based access.

Alternatives

Additional Context

[svenseeberg]

We probably need some sort of one time pad / token that allows editing for a limited time. This is also the case in #316.