Implemented:
* Account Connect
* Calendar sync via delta ids then requesting single events
I think I would split the messaging part into a second pr - that's a
step more complex then the calendar :)
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Co-authored-by: bosiraphael <raphael.bosi@gmail.com>
- Refactor calendar modules and some messaging modules to better
organize them by business rules and decouple them
- Work toward a common architecture for the different calendar providers
by introducing interfaces for the drivers
- Modify cron job to use the new sync statuses and stages
