Should record these metrics in the DonorShardEntry of the coordinator document.

Donor shards report these numbers for their slice of the data when reporting their minFetchTimestamp and for the coordinator to propagate the sum to recipient shards

metrics source:
https://github.com/mongodb/mongo/blob/06b4a33530bfd58fab55e1fdda506b51f75f1ec5/src/mongo/db/catalog/collection.h#L526-L528

update minFetchTimestamp for the coordinator:
https://github.com/mongodb/mongo/blob/06b4a33530bfd58fab55e1fdda506b51f75f1ec5/src/mongo/db/s/resharding/resharding_donor_service.cpp#L436