Changes to Get usage breakdown by request endpoint

for the query request parameter auth_key_id, the type was generalized from string to array

for the query request parameter endpoint, the type was generalized from string to array

for the query request parameter label, the type was generalized from string to array

for the query request parameter model, the type was generalized from string to array

for the query request parameter provider, the type was generalized from string to array

for the query request parameter user_path, the type was generalized from string to array

added the optional property items/billed_cost to the response with the 200 status

endpoint added