Google calendar event link generator

1. Use GoogleCalendarLink.Builder class for creating link object
2. Use GoogleCalendarLinkServiceImpl.generate() class for generating link
3. Check GoogleCalendarLinkServiceTest out as an example of usage

        var calendarLink = new GoogleCalendarLink.Builder("Weekly Stand Up", startTime, endTime)
               .location("Kyiv, Ukraine")
               .addGuest("[email protected]")
               .description("Discuss current state of the project")
               .availability(GoogleCalendarLink.AVAILABILITY.BUSY)
               .build();
   
       var calendarLinkService = new GoogleCalendarLinkServiceImpl();
       var link = calendarLinkService.generate(calendarLink);