Function relation_resolution 

fn relation_resolution<'a>(
    project: ProjectInstanceId,
    generation: IndexGeneration,
    relation: &SymbolRelation,
    owners: &GraphOwners,
    graph: &SymbolGraph,
    symbol_index: &GraphSymbolIndex<'_>,
    dependency_keys: &[CanonicalResolutionKey],
    candidates: &'a ProjectResolutionRegistry,
    staged_entities: &'a BTreeMap<String, GraphEntity>,
    external_entities: &mut BTreeMap<String, GraphEntity>,
    control: &IndexWorkControl,
) -> Result<RelationResolution, CliError>

Resolve one relation from canonical dependency keys and bounded candidates.