BO16 - Create a DAL function to list all Sponsorship levels and Sponsors

[gregoriopalama]

Add a DAL function in the Sponsorship API.

The response will be a list of partnership levels and partners, as for the example below. Use the example as a reference for a level's and a partner's structure.

[
    {
        "id": "ID",
        "name": "Main Sponsor",
        "position": 0,
        "partners": [
            {
                "id": "ID",
                "name": "Google",
                "logo": "LINK TO THE LOGO",
                "position": 0,
                "link": "https://www.google.com"
            }
        ]
    },
    {
        "id": "ID",
        "name": "Community Partner",
        "position": 1,
        "partners": [
            {
               "id:"ID",
                "name": "GDG Pescara",
                "logo": "LINK TO THE LOGO",
                "position": 0,
                "link": "https://www.gdgpescara.it"
            }
        ]
    }
]

The function should support pagination, providing informations in the response and handling pagination request. The paginations should be only on Sponsorship levels: all the sponsors in the single level will be listed.