Function map_column_refs 

pub(super) fn map_column_refs(
    retrieved_references: &RetrievedSourceReferences,
    columns: &mut [UnresolvedItemName],
    option_type: PgConfigOptionName,
) -> Result<BTreeMap<u32, BTreeSet<String>>, PlanError>

Map a list of column references to a map of table oids to column names.

Additionally, modify columns so that they contain database-qualified references to the columns.