Data items in the MA_QA_METRIC_FEATURE_PAIRWISE category captures the
QA metrics calculated per pair of features as defined in ma_feature_list.
In cases where the metric is symmetric, it is enough to store just one value per pair.
For asymmetric metrics, the order of features is expected to be meaningful
(e.g. PAE where PAE_ij is defined by aligning token i (feature_id_1) and measuring
the error on token j (feature_id_2)).
It is valid to only provide values for a subset of feature pairs.
Data in this category is expected to be very large and can be extracted into a
separate file which is linked to the main file using the categories
ma_associated_archive_file_details or ma_entry_associated_files with file_content
set to "QA metrics".