rcv: RV Entry of factura exportación has blank receptor razón social

[sentry-io]

Can a RvDetalleEntry of a (non-electronic) factura de exportación (<RcvTipoDocto.FACTURA_EXPORTACION: 101>) have a blank (empty string) receptor razón social?

Sentry Issue: FD-CL-DATA-13F

ValueError: Value must not be empty.
  File "cl_sii/rcv/parse_csv.py", line 1175, in _parse_rcv_csv_file
    entry = input_csv_row_schema.to_detalle_entry(deserialized_row_data)
  File "cl_sii/rcv/parse_csv.py", line 651, in to_detalle_entry
    detalle_entry = RvDetalleEntry(
  File "<string>", line 13, in __init__
    from typing import Optional
  File "cl_sii/rcv/data_models.py", line 244, in __post_init__
    cl_sii.dte.data_models.validate_contribuyente_razon_social(self.receptor_razon_social)
  File "cl_sii/dte/data_models.py", line 76, in validate_contribuyente_razon_social
    raise ValueError("Value must not be empty.")

Deserialized data to data model instance conversion failed (probably a programming error).

[glarrain]

CC @yaselc @yanosky

[yaselc]

CC: @ycouce-cdd