fix(vsup_stag): update service for new DB schema
Created by: zlamalp
- We now have two tables, for students and for teachers.
- Employees are not supported in STAG.
- For now we do not set "working position" of teachers and we do not set photo for any type of person.
- Since tables are live views we only update students (based on their RC) and never delete or insert them. We always update all columns, otherwise it would be considered as delete for the column value.
- Teachers are live view too, but we insert new persons this way. All updates are done based on their UCO_PERUN in a similar manner to the students.