Fix non-portable path serialization in ProjectNode.

This was failing snapshot tests on the Linux CI machines,
since I committed snapshots with backslashes.

I think the old path serializer was still the wrong approach,
this one is sort of a middleground but I'm still not super
happy with it.

src/path_serializer.rs

@@ -36,3 +36,17 @@ where
 
     seq.end()
 }
+
+pub fn serialize_option_absolute<S, T>(
+    maybe_path: &Option<T>,
+    serializer: S,
+) -> Result<S::Ok, S::Error>
+where
+    S: Serializer,
+    T: AsRef<Path>,
+{
+    match maybe_path {
+        Some(path) => serialize_absolute(path, serializer),
+        None => serializer.serialize_none(),
+    }
+}

src/project.rs

@@ -269,6 +269,8 @@ pub struct ProjectNode {
     pub children: BTreeMap<String, ProjectNode>,
     pub properties: HashMap<String, UnresolvedRbxValue>,
     pub ignore_unknown_instances: Option<bool>,
+
+    #[serde(serialize_with = "crate::path_serializer::serialize_option_absolute")]
     pub path: Option<PathBuf>,
 }
 

src/snapshots/serve_session__change_file_in_project_after.snap

@@ -29,7 +29,7 @@ children:
             children: {}
             properties: {}
             ignore_unknown_instances: ~
-            path: "/foo\\file.txt"
+            path: /foo/file.txt
       relevant_paths:
         - /foo/file.txt
         - /foo/file.meta.json

src/snapshots/serve_session__change_file_in_project_before.snap

@@ -29,7 +29,7 @@ children:
             children: {}
             properties: {}
             ignore_unknown_instances: ~
-            path: "/foo\\file.txt"
+            path: /foo/file.txt
       relevant_paths:
         - /foo/file.txt
         - /foo/file.meta.json