rust-core: add missing `Debug` traits

Turns out you need them when trying to use `hg-core` as a library. Who knew.

Differential Revision: https://phab.mercurial-scm.org/D8278

rust/hg-core/src/dirstate/status.rs

@@ -623,6 +623,7 b" fn extend_from_dmap<'a>("
     );
 }
 
+#[derive(Debug)]
 pub struct DirstateStatus<'a> {
     pub modified: Vec<Cow<'a, HgPath>>,
     pub added: Vec<Cow<'a, HgPath>>,
@@ -679,6 +680,7 b" fn build_response<'a>("
     )
 }
 
+#[derive(Debug)]
 pub enum StatusError {
     IO(std::io::Error),
     Path(HgPathError),

rust/hg-core/src/lib.rs

@@ -103,6 +103,7 b' impl ToString for DirstateMapError {'
     }
 }
 
+#[derive(Debug)]
 pub enum DirstateError {
     Parse(DirstateParseError),
     Pack(DirstatePackError),