Add schedule import to Google Calendar

[Markusplay]

Create a feature that allows users to import their group schedule into Google Calendar. The endpoint should receive a group from the client, then we need to fetch the group's schedule from campus API https://api.campus.kpi.ua/swagger/index.html and import the schedule into Google Calendar. The current version of this feature is sr.kpi.ua/rozklad. The issue with the current system is that it imports schedule on the two weeks at the start of the semester. New import should import correctly on the full semester

[yarman1]

The feature has the following flow:

1. The interface calls the authorization endpoint to obtain the necessary permissions.
2. The backend redirects to a special page of the interface, where the user can select needed pairs.
3. The interface sends the necessary json data.