pub(crate) fn load_generator_ast_to_generator(
scx: &StatementContext<'_>,
loadgen: &LoadGenerator,
options: &[LoadGeneratorOption<Aug>],
include_metadata: &[SourceIncludeMetadata],
) -> Result<(LoadGenerator, Option<BTreeMap<FullItemName, (RelationDesc, LoadGeneratorOutput)>>), PlanError>