Enhance CloneCommand and Syncback functionality

- Added a check in `CloneCommand` to prevent cloning into an existing directory, providing a clearer error message for users.
- Updated the `SyncbackCommand` to support a configurable working directory for resolving relative paths, improving flexibility in project structure.
- Refactored the commit message in the `CloneCommand` to accurately reflect the syncback operation.
- Improved path resolution logic in `SyncbackCommand` to handle both absolute and relative paths more effectively.

tests/rojo_test/internable.rs

@@ -38,7 +38,10 @@ impl Internable<Ref> for ReadResponse<'_> {
         redactions.intern(root_id);
 
         let root_instance = self.instances.get(&root_id).unwrap();
-        intern_variant_refs(redactions, root_instance.properties.values().map(|v| v.as_ref()));
+        intern_variant_refs(
+            redactions,
+            root_instance.properties.values().map(|v| v.as_ref()),
+        );
 
         for &child_id in root_instance.children.iter() {
             self.intern(redactions, child_id);