Investigate allow querying allocations API using body payload

[QuanMPhm]

As discussed in here, currently for billing purposes, we plan on querying the allocations API and filter it to only find projects present in our monthly invoice. Our method of querying is create a giant query URL, containing all invoice project names. This seems like a rather unusual and funny way of using URLs.

Before using the URL query eventually becomes a problem, we should investigate allowing filtering through the body payload instead of URL queries.