dirstatemap: use a common implementation for `dirstatemap.set_untracked`...
dirstatemap: use a common implementation for `dirstatemap.set_untracked`
We can now make sure they use the same code, and drop the older, out of sync,
implementation of `set_untracked` for the rust wrapper.
Differential Revision:
https://phab.mercurial-scm.org/D11572