fix(BA-596): Add project_node field to GQL UserNode type

[fregataa]

resolves #3526 (BA-596)

GQL query example

query UsersQuery {
    user_nodes{
        edges {
            cursor
            node {
                id
                email
                project_nodes {
                    edges {
                        node {
                            id
                            name
                        }
                    }
                    count
                }
            }
        }
        count
        pageInfo {
            hasNextPage
            hasPreviousPage
        }
    }
}

Checklist: (if applicable)

• Milestone metadata specifying the target backport version
• Mention to the original issue