Mercurial: Provide chg binary
Since Mercurial is built with rust enabled it can provide the daemon helper of hg. That allows faster start ups of python based hg binary.
https://www.mercurial-scm.org/repo/hg/file/default/rust/chg
It is the rust edition of the old chg client https://www.mercurial-scm.org/repo/hg/file/default/contrib/chg