[#13144] Copy students from existing students table to new students table

[NeoHW]

Fixes #13144

Outline of Solution

Motivation and Context

For instructors who want to batch edit many students, they would have to copy and paste the whole sheet from existing students manually. The slightly clunky cell selection in the sheet would make it sometimes hard to select all students, especially if there are many students. Therefore, I would suggest the addition of a button to auto-import existing students into the new students sheet below. This would be a QOL change and also helps when instructors want to mass-edit students.

Changes

Frontend:

1. Added a copy students button on the enrol page and formatted it.

Backend:

1. Created functionality to copy existing students' spreadsheets into new students' spreadsheet
   • Ran into the issue that Existing students' spreadsheet has to be expanded for logic to work
   • Another issue was the asynchronous nature of fetching data with API calls in toggleExistingStudentsPanel
2. Modify toggleExistingStudentsPanel to take in an optional callback
   • This ensures that the data is only copied after it has been successfully loaded

Video Demo

Before:

https://github.com/user-attachments/assets/a5cbb0d2-bd77-4b21-b254-388f52fad915

After:

https://github.com/user-attachments/assets/e3b2a84c-10e3-4992-94c8-7a99269f92dc

[github-actions[bot]]

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[nusoss-bot]

Folks, This PR seems to be stalling (no activities for the past 7 days). :snail: :cry: Hope someone can get it to move forward again soon...