geotiff: Make CRS resolution async?

[kylebarron]

developmentseed/async-geotiff#125 showed that sometimes to resolve custom CRSes there isn't a full description of the CRS embedded in the geokeys. Sometimes we'll have to make queries to the other elements of the EPSG database, such as Ellipsoid or CoordinateOperation

We may want to support fetching epsg.org's API for this. See docs and swagger json.

E.g. for the file in developmentseed/geotiff-test-data#35 we have to look up the 16052 CoordinateOperation. This is easy in python with pyproj but in TS we'd either need to bundle it or provide an async API.