Add subtable writer for input streaming step
DP3 requires a measurement set to start reading data. The reason why is that the MS contains additional tables, which contain ancillary information about the observation or the antenna for example.
In this branch there is the implementation of object that helps the creation of such additional tables. This is required for the AARTFAACReader step which is able to read file containing UDP packets from the AARTFAAC correlator.