called by readHFDweb(). This assumes that CNTRY is actually available in the HFD.
getHFDitemavail(CNTRY)a tibble of all available data files for the selected country. There are several useful identifiers that can help determine the appropriate file, including the `measure` and `subtype` as detected from the html table properties, and `lexis` and `parity` as detected either from the file names or the table properties.
HFD country short code.