Function append_shuffled_templates_cached 

fn append_shuffled_templates_cached<'a>(
    pool: &'a TemplatePoolData,
    cache: &mut FxHashMap<Identifier, Vec<&'a PoolElement>>,
    rng: &mut LegacyRandom,
    out: &mut Vec<&'a PoolElement>,
)

Appends vanilla’s StructureTemplatePool.getShuffledTemplates to out.