AASHTO-2023 web service -- add CSV response

Draft format of the CSV ...

USGS AASHTO-2023 Web Service

Request: Latitude (degrees), 34.05 Longitude (degrees), -118.25 Site Class, D

Response: Period (s), Spectral Acceleration (g) 0, 0.67 0.01, 0.67 0.02, 0.67 0.03, 0.68 ...