dirstate-tree: Empty shell for a second Rust DirstateMap implementation For background see description of the previous changeset "Make Rust DirstateMap bindings go through a trait object". Add an empty shell for a opt-in second Rust implementation of the `DirstateMap` type and the `status` function. For now all methods panic. This can be seen in "action" with: ./hg status --config experimental.dirstate-tree.in-memory=1 Differential Revision: https://phab.mercurial-scm.org/D10364

--- a/rust/hg-core/src/dirstate_tree.rs	Thu Apr 08 14:58:44 2021 +0200
+++ b/rust/hg-core/src/dirstate_tree.rs	Tue Mar 30 09:56:04 2021 +0200
@@ -1,1 +1,2 @@
+pub mod dirstate_map;
 pub mod dispatch;