Add user role for translations

[osmers]

Motivation

Some municipalities have people dedicated to correcting translations - it might be helpful to give them their own role.

Proposed Solution

Add user role "translator" and select languages for this role in the user settings.
The role should have the following rights

• change/publish content in their assigned language(s)
• see page tree only in their assigned language
• see German pages but have no publish/ammend rights (similiar to observer role)

Alternatives

Keep current role set up which allows users to either change and submit for review or change and publish across all languages.

User Story

As an admin for a municipality I want an easy way to assign other users to review translations without having to worry about them changing something in German

Additional Context

Design Requirements

Related Issues