PADRE-2: Added alternative AntennaFlagger based on aartfaac-tools

This is a follow-up MR to !667 (merged) where we integrated the flagging functionality of this Python script into AntennaFlagger the form of high-performance (albeit sequential) C++ code. In its current state, AntennaFlagger is intended to replace all the separate calls (e.g. to aoquality, aoflagger, a Python script and DP3) by a single DP3 step. This is not only much simpler, but also much faster.

The C++ flagging code was originally developed as part of this, but for the sake of integrating it into DP3, it was copied into the DP3 repository and refactored according to the review comments raised in !667 (merged).