[Feature Suggestion] Import external Calendars

I suggest to IMPORT events from external calendar into Quire.

The goal is to know if there are already external time slots, with events in that calendar, that can't be assigned to tasks.

Examples: holidays, days-off, personal and medical appointments, and for students, classes and lectures to attend.

Import from: Google Calendar, Apple Calendar, Proton Calendar (https://proton.me/calendar) or Moodle (https://docs.moodle.org/401/en/Using_Calendar).

No need to edit them in Quire, just view them, and if they are updated into the external app, changes are automatically applied to imported calendars.

Many thanks!