rust: Add Repo::dirstate_map and use it in `rhg status`...
rust: Add Repo::dirstate_map and use it in `rhg status`
This moves low-level dirstate wrangling out of the status command and into
a more reusable location.
The open dirstate map is lazily initialized and kept on the Repo object,
for reuse by sub-sequent calls.
Differential Revision:
https://phab.mercurial-scm.org/D11398
