[New app] Gradebook

Requirements from @fph

Goal: Get a quick overview about the performance of a student/group

1. 2FA necessary for all grade data (configurable, https://www.gesetze-rechtsprechung.sh.juris.de/bssh/document/jlr-SchulDSVSH2018V2P13)
2. Show grades on person page (later)
3. Management pages for grade sets with choices and rating types
4. Show grades as tab on group page
   1. Simple table with direct input fields for grades
   2. Add button for new columns aka ratings
   3. Tab order has to be correct
   4. Auto save
5. On parent group page, all grades from child groups shall be shown (filterable by rating type, course group)
6. Printout of grading tables (e. g. for conferences or archiving)

Blocking: AlekSIS/official/AlekSIS-Core#122 (closed) for group page

Relations

• GradeChoice(set → GradeSet, name, value, order)
• GradeSet(name)
• EffortType(name, color)
• Effort(name, type → EffortType, weight, group → Group)
• Grade(grade → GradeChoice, rating → Rating)