rust-status: add bare `hg status` support in hg-core A lot of performance remains to be gained, most notably by doing more things in parallel, but also by caching, not falling back to Python but switching to another regex engine, etc.. I have measured on multiple repositories that this change, when in combination with the next two patches, improve bare `hg status` performance, and has no observable impact when falling back (because it does so early). On the Netbeans repository: C: 840ms Rust+C: 556ms Mozilla Central with the one pattern that causes a fallback removed: C: 2.315s Rust+C: 1.700 s Differential Revision: https://phab.mercurial-scm.org/D7929

rust-status: add function for sequential traversal of the working directory This change also introduces helper structs to make things clearer. Differential Revision: https://phab.mercurial-scm.org/D7928

rust-status: add missing variants to `Dispatch` enum Differential Revision: https://phab.mercurial-scm.org/D8088

rust-status: rename `StatusResult` to `DirstateStatus` "Result" has a special meaning in the Rust world, this should be clearer. Differential Revision: https://phab.mercurial-scm.org/D8087

rust-status: refactor options into a `StatusOptions` struct Differential Revision: https://phab.mercurial-scm.org/D8086

rust-status: add util for listing a directory I debated moving it to utils, but it is not used anywhere else for now, and its skip behavior is pretty specific to status. Differential Revision: https://phab.mercurial-scm.org/D7927

rust-matchers: add `IgnoreMatcher` This is a big change but all of the pieces call each other, so it makes sense to have this all in one patch. Differential Revision: https://phab.mercurial-scm.org/D7925