Update the APIs to include `EndTime` and `Date` of a placment drive

[Doraemon012]

Is your feature request related to a problem? Please describe.

The backend currently doesn't support handling the new "End Date & Time" and "Eligibility Criteria" fields for placement events.

Describe the solution you'd like

Update the backend to:

• Store the End Date & Time for placement events and ensure the form closes after the specified time.
• The form should automatically close after the End date & Time
• Allow for Eligibility Criteria to be stored as a list of values (e.g., "CSE", "8 CPI").
• Ensure that these fields are properly passed and saved when creating or editing placement events.

Describe alternatives you've considered

None, as we need a backend solution to store and manage these new fields for placement events.

Additional context

Look at this issue and the related PR for the UI context