AssignGenes.py igblast --format airr does not introduce the IMGT-gaps spacers as with AssignGenes.py igblast --format blast

[gael-millot]

This concerns the sequence_alignment and germline_alignment columns, as described in
https://docs.airr-community.org/en/stable/datarep/rearrangements.html#fields
At least, these two column would required a deeper description. Thanks