include taxonRankID in the combined names index

[adam-collins]

The combined version of the names index (found here) does not include http://rs.tdwg.org/dwc/terms/taxonRankID. This is required to stop the bie-index from returning different values.

When bie-index imports a DwCA it uses its own rankID lookup. This already differs from RankType.java. e.g. ALA reports different rankID values for the same species bie-index and ala-namematching-service

Imagined options

• My preference is to add taxonRankID to the combined index. The intention is that bie-index will use this instead of the unmaintained lookup.
• My second preference is to add the RankType.java information into the combined archive. This would be used by the bie-index in place of taxonRanks.json. An advantage is that bie-index service ws/ranks would not require an update.
• Lastly, when a new index is released the taxonRanks.json file will be kept up to date manually. This is not preferred because it has a history of not taking place, it would require maintaining an additional file, and more closely tie bie-index versions to particular index versions.