Given a single row data.table, convert it into a named vector. Used in the mvn_inference, to obtain an evidence named vector. For this case, the data.table should contain only the evidence that we want to provide. If a named vector is provided instead of a data.table, nothing will be done and the named vector will be returned.
as_named_vector(dt)
a named vector with the values and the variable names
a 1 row data.table or a named vector