This function is an internal utility that fills in custom RDMs using

particle RDMs. The result of Wick's theorem is passed as lists (indices and delta) and a factor associated with it. The results are stored in target.

target (numpy.ndarray) - output array that stores reordered RDMs

source (numpy.ndarray) - input array that stores one of the particle RDMs

indices (List[int]) - index mapping

factor (float) - factor associated with this contribution

delta (List[Tuple[int, int]]) - Kronecker delta's due to Wick's theorem