geotiff: Make CRS resolution async?

https://github.com/developmentseed/async-geotiff/pull/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](https://apps.epsg.org/api/swagger/index.html) and [swagger json](https://apps.epsg.org/api/swagger/v1/swagger.json).

E.g. for the file in https://github.com/developmentseed/geotiff-test-data/pull/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.