Event Saving and Remove Register Event Desktop

[AndrewHUNGNguyen]

• Removed Register Event on Desktop for individual event with a custom MobileAttendButton that appears on mobile display of DEVxSD only
• Added ability to save upcoming events
  • Created a database table called event_interest to store events that users save
  • included save event button on individual events so that users can save events to store in the Saved Events UI
  • included functionality to block users from saving events if not logged in to their account