Input and export scipy.cluster.hierarchy lineage matrix format

[hyanwong]

Import code already exists here: we just need to move it into tsconvert.

https://github.com/jeromekelleher/phylokit/blob/main/phylokit/inference.py

Some details of Newick<->lineage matrix here: tskit-dev/tskit#3159 (comment) which might help export, I guess?