Google Calendar Integration for Events

[ambers7]

Summary

This pull request implements Google Calendar integration for Campus Events. It takes in a CampusEvent, gets the event title, description, start/end time, and location, and creates a Google Calendar invitation link that fills in the information in their respective places.

Handles both timed events and all-day events. All day events are marked as such (allDay= true) in the CampusEvent.

• created a function to create a Google Calendar event URL using Dart's Uri class.
• made helper functions to convert a CampusEvent DateTimes for startTime and endTime into UTC times that follow the Google Calendar format (YYYYMMDD for all day events and YYYYMMDDTHHmmssZ for timed events).
• tested creation of GCal URLs of different timed and all day events manually

[dti-github-bot]

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