ENH: Better information on private mutations

[corneliusroemer]

Right now we break up private mutations into: labeled, unlabeled and reversions.

For monkeypox, I noticed that it would be nice to see sometimes if a mutation was simply already found at least once on the tree (or in other sequences uploaded).

In a similar way to a "labeled" mutation - but with a different meaning - and generated dynamically based on the tree (and other sequences, maybe) and not as part of the dataset.

Similar to how Auspice groups mutations into a) Unique and b) Homoplasies

When I hover over nuc mutations, it's right now impossible to see if they are a) unique, b) labelled, c) present in ref tree but not labeled