Preprocess host-species into a smaller list

[j23414]

Context

• What are the main host species for WNV?
• Can we summarize the current list into those main species?

Examples

Current list seems more detailed than useful.

Full list here: host.txt

Possible solution

After we have main host categories, we may be able to reuse the method from the rabies workflow

• https://github.com/nextstrain/rabies/commit/618bbd5601985ba7c6bda973f08a70f3a8b3266b#diff-035eb13b0d51608579a8ccff585fa32ce5a444c80cc4f76655322f50c2c01a6f

[joverlee521]

An additional use case of curating host values would be extremely useful for building out a shared command in https://github.com/nextstrain/augur/issues/1586!