Update get mentor categories endpoint (public) to send category IDs

Description: Currently, the api/categories endpoint only returns a list of category names. The category IDs are required during the mentor application process.

Tasks: Add the category IDs to the response.

Acceptance Criteria: Should be able to get all categories with their IDs.

Sample response:

{
"categories": [
    {
        "category": "Data Science",
        "id": "95ba00c0-8173-43c4-9573-6b481b4085e2"
    },
    {
        "category": "Random Category",
        "id": "fe7ca629-4f5e-440a-86cb-d54f8b98ec5f"
    },
    {
        "category": "Computer Science",
        "id": "fef68adb-e710-4d9e-8772-dc4905885088"
    }
],
"message": "All Categories found"
}

Additional Information: Endpoint implemented with #16

Related Dependencies or References:

sef-global / scholarx-backend

Update get mentor categories endpoint (public) to send category IDs #82