[FR] Implement an oData filter builder

[HelgeSverre]

To make it easier to work with oData filters, a builder should be created.

Example of how this would look like in practice:

<?php 

$customerQuery = oDataQuery::query()
     ->LessThanOrEqual("CustomerNumber" , 100)
     ->orderByAsc("Name");

// Fetch only customers where the CustomerNumber is less than or equal to 100, and order by the Name ascending.

$service->getCustomers($customerQuery);

$customerQuery->build(); // "?$filter=(CustomerNumber le 100)&$orderBy=Name asc"