- Create hir_crate_items query which traverses tcx.hir_crate(()).owners to return a hir::ModuleItems
- use tcx.hir_crate_items in tcx.hir().items() to return an iterator of hir::ItemId
- add par_items(impl Fn(hir::ItemId)) to traverse all items in parallel
Signed-off-by: Miguel Guarniz <mi9uel9@gmail.com>