Add Rake Tasks for Fetching Past Events

[marcoroth]

This pull request introduces functionality to fetch and manage past meetup events alongside existing capabilities for upcoming events. We added new tasks for fetching past meetups, extending the data model and GraphQL schema to support past events, and updating the logic for handling past events.

New Rake Tasks for Past Meetups:

• Added :fetch_past_meetups task to fetch all past meetup groups and save them to the meetups file.
• Added :fetch_past_meetup task to fetch past meetups for a specific group by group_id.

This is in preparation to backfill the meetups so we can bring over a complete list of meetups when we migrate the data to RubyEvents.org.

[marcoroth]

I let it run for all meetup groups and committed the result in 47dc91d, might be a bit too much 🙈