update show_student_extensions api to DRF

[awais786]

Verify via postman

1: Try this URL in postman
2: form-data: pass ket as student: admin or your student user name.

expected result

{
    "header": [
        "Unit",
        "Extended Due Date"
    ],
    "title": "Due date extensions for abc qdd (admin)",
    "data": [
        {
            "Unit": "intro to testing",
            "Extended Due Date": "2024-08-31 13:07"
        }
    ]
}

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Verify via instructor Dashboard

1. Try this URL
2. pass student user name.

expected result