[Feature Request] Allow members to register for free events

[phoenixpereira]

Overview

Allow members to register for free events easily through the website.

Details

• Update the db to have an attendees table with the user's id, keycloak id, name, and dietary requirements (string).
• Check Payload CMS to see if an event is catered or not to conditionally show the dietary requirements modal.
• Add modal pop up on events page when you click on an event card for registering your interest, can be simple button on event card for non-catered events

Why would this feature be useful?

So that people can easily register your interest in events and add any dietary requirements. It also makes it easier for the committee to organise how much food to get for catered events.

Additional Notes

Requires #256 to be finished first. Would be nice to support paid events as well with the Square API.