Enforce reviewer policy on Weblate

Originally created by @intrigeri on #16855 (Redmine)

I.e. enforce “one needs to have Reviewer status to be allowed to accept suggestions” and make sure that non-admin users can’t change this setting per-component.

Blueprint: https://tails.boum.org/blueprint/translation_platform/#access-control

Related issues

• Related to tails/sysadmin#16881
• Related to tails/sysadmin#16989
• Blocks tails/tails#16326