Move [Aa]ncestors to under commit module

In preparation of a new module for topological commit walk. The idea is
that the current walk will be the "default" hence the 'pub use'.

Author: Osse

gix-traverse/src/commit.rs renamed to gix-traverse/src/commit/ancestors.rs

@@ -100,7 +100,7 @@ pub mod ancestors {
     use gix_object::{CommitRefIter, FindExt};
     use smallvec::SmallVec;
 
-    use crate::commit::{collect_parents, Ancestors, Either, Info, ParentIds, Parents, Sorting};
+    use super::{collect_parents, Ancestors, Either, Info, ParentIds, Parents, Sorting};
 
     /// The error is part of the item returned by the [Ancestors] iterator.
     #[derive(Debug, thiserror::Error)]
@@ -455,6 +455,8 @@ pub mod ancestors {
     }
 }
 
+pub use ancestors::{Error, State};
+
 enum Either<'buf, 'cache> {
     CommitRefIter(gix_object::CommitRefIter<'buf>),
     CachedCommit(gix_commitgraph::file::Commit<'cache>),

gix-traverse/src/commit/mod.rs

@@ -0,0 +1,3 @@
+/// Simple ancestors traversal
+pub mod ancestors;
+pub use ancestors::{Ancestors, Info, ParentIds, Parents, Sorting};