schemas: update /schemas /collections/.. endpoint for permissions

[pamfilos]

We should make the response structure for the collections to be like:

{
    "deposit-admin": {
        "roles": [],
        "users": [
            {
                "email": "[email protected]",
                "profile": {}
            }
        ]
    },
    "deposit-read": {
        "roles": [],
        "users": [
            {
                "email": "[email protected]",
                "profile": {}
            },
            {
                "email": "[email protected]",
                "profile": {}
            }
        ]
    },
    "deposit-update": {
        "roles": [],
        "users": [
            {
                "email": "[email protected]",
                "profile": {}
            }
        ]
    }
}