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