Annotate titers per node

[huddlej]

Context

We need to know which strains and clades do not have titer measurements from different assays, passage types, and sources. We previously wrote a script to annotate the number of titer measurements per node as a node data JSON file. This script's output plus an Auspice config JSON coloring entry allowed us to color the tree by total titers or counts binned into larger categories.

Description

We should implement this annotation in the refactored workflow for the private builds, at least. We could also use the Auspice config JSON to setup meaningful bins for the counts as a legend scale.

It would also be helpful to be able to filter the tree by presence/absence of mutations in the different categories, so we could focus on only tips that have no measurements.

[huddlej]

This issue was resolved with a custom script and Snakemake rule in the nextflu-private workflow.