rust-dirstatemap: cache non normal and other parent set Performance of `hg update` was significantly worse since the introduction of the Rust `dirstatemap`. This regression was noticed by Valentin Gatien-Baron when working on a large repository, as it goes unnoticed for smaller repositories like Mercurial itself. This fix introduces the same getter/setter mechanism at `hg-core` level as for `set/get_dirs`. While this technique is, as previously discussed, quite suboptimal, it fixes an important enough problem. Refactoring `hg-core` to use the typestate pattern could be a good approach to improving code quality in a future patch. Differential Revision: https://phab.mercurial-scm.org/D8048