feat: Display Usernames Instead of Emails in Attendance Section in the Professor's Dashboard

[divyamagrawal06]

Title: feat: Use Usernames in Attendance Section

Description:

Update the attendance section to display usernames instead of email addresses.

Why:

• Improves readability and scannability.
• Enhances user privacy by not exposing emails.

Acceptance Criteria:

• Fetch and display usernames in the attendance list.
• Replace all instances of email addresses with usernames in this component.
• Implement a fallback (e.g., "Guest") for users without a username.