Check-in admin portal setup

[waalbert]

Changes

• Hides badge number from participants table used for check-in
  • Note: badge_number is still part of the class Participant and list PARTICIPANT_FIELDS
• Removes badge scanning and badge number entry in confirmation check-in modal
• Also removes badge scanning and badge number entry for Event check-ins
  • Note: For IH 25, event check-ins will not be done through our site
• Sets up notifications system and clears all notifications on page change
• Notifications will be pushed to the notifications system as Flashbars that show at the top of the admin layout

Testing

1. Ensure you can see the participant table and be able to check-in people.
2. Upon clicking "Check In" in the confirmation check-in modal, notice that a new Flashbar gets added to the top of the screen as part of the notifications Flashbar system

Closes #593 and closes #407

[github-actions]

Deploy preview for irvinehacks-site-2025 ready!

Name	IrvineHacks Site
Preview	Visit Preview
Commit	2df0695