Multipurpose function to find a COMID of interest.
Note that NHDPlusV2 uses "featureid" for catchment polygons and "comid" for
flowline linestrings. These two identifiers are the same where a
flowline/catchment pair exists. In some cases, a catchment will not have a
flowline and in others, a flowline will not have a catchment.
If a point is provided, and raindrop is false, the comid/featureid integer
of the catchment the point is in is returned. This options uses a web
service here:
https://api.water.usgs.gov/fabric/pygeoapi/collections/catchmentsp
If a point is provided, and raindrop is true, the response is the result of
a call to get_raindrop_trace.
If no point is provided, the raindrop argument is ignored and the result
is a comid integer derived from a call to get_nldi_feature.