Concurrent iterator methods for go-amt-ipld and go-hamt-ipld #21
Description
Based on filecoin-project/go-hamt-ipld#103
We need versions of the ForEach methods for both go-amt-ipld and go-hamt-ipld that perform a concurrent iteration.
We also need versions of these concurrent methods that support selector suffix and internal node extraction (combination with #17)
If we want to leverage batch reads from the backing blockstore (as shown in filecoin-project/go-hamt-ipld#103), we also need a blockstore implementaiton for badgerdb that supports a GetMany interface.
Used by #16