BC-11106: Clean-up and invitation mail content generation

[sebmue-dataport]

Description

Clean-up and registration invitation email content generation

Links to Tickets or other pull requests

• https://ticketsystem.dbildungscloud.de/browse/BC-11106

Changes

• The Permission SCHOOL_MANAGE_ROOM_INVITATIONLINKS is used to determine access
• A migration ensures SCHOOL_MANAGE_ROOM_INVITATIONLINKS is given to users
• The mail content for invitations is generated in German and English
• HTML-Sanitization is added to the Invitation Body Params

Approval for review

• DEV: If api was changed - generate-client:server was executed in vue frontend and changes were tested and put in a PR with the same branch name.
• QA: In addition to review, the code has been manually tested (if manual testing is possible)
• All points were discussed with the ticket creator, support-team or product owner. The code upholds all quality guidelines from the PR-template.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud