AddEvent form verification and QOL

[peterchinh]

Description
Whenever a user clicks "Continue" on the AddEvent panels, check/validate the required inputs (ie Title, Date, Time, Location)

Since you also need to check for virtual location, also add an input box for that.

Acceptance Criteria
A clear and concise description of what you want to happen.

Steps:

• Add a check function before continuing to next panel in the button onClick
• Add virtual location meeting link input on AddEventLocationPanel
• Add back buttons to each panel
• Add a Close Icon to each panel
• Display the relevant error message
• Remove long/lat display on AddEventLocationPanel

Additional Information
Add any other context or screenshots about the feature request here.