Context

Sometimes one wants to use multiple independent clade systems, like clade, outbreak, lineage in monkeypox or whole genome clade and G gene clade in RSV

Right now, augur clades always outputs a node data json with a magic fixed key clade_membership.

It would be nice if one could optionally adjust this key name through a CLI argument to augur clades.

That would save a lot of sed commands that are necessary otherwise in multiple scripts.