Handle Vs30 Map Attribute

Currently site class vs30 map is incorrect.

Need to handle the new attribute that has the correct mapping.

Require https://code.usgs.gov/ghsc/nshmp/nshmp-netcdf-conversion/-/issues/23

changed milestone to %NSHM Hazard Tool Launch - 2

added To Do label

assigned to @bclayton

mentioned in issue nshmp-apps#81 (closed)

added In Progress label and removed To Do label

mentioned in merge request !102 (merged)

mentioned in commit 086750a8

closed with merge request !102 (merged)

removed In Progress label