Implement sync source-only mode in ServeSession and ChangeBatcher

- Added support for a new sync mode in ServeSession that filters property changes to only include the Source property when the server indicates it is in source-only mode.
- Updated ChangeBatcher to handle the new syncSourceOnly parameter, ensuring that only relevant property changes are processed based on the server's capabilities.
- Enhanced API response to include sync_source_only flag, indicating the server's sync capabilities.
- Adjusted related functions to accommodate the new sync logic, improving data synchronization efficiency.

src/web/interface.rs

@@ -165,6 +165,10 @@ pub struct ServerInfoResponse {
     pub game_id: Option<u64>,
     pub place_id: Option<u64>,
     pub root_instance_id: Ref,
+    /// When true, the server only supports syncing script Source property changes.
+    /// Other property changes will be ignored.
+    #[serde(default)]
+    pub sync_source_only: bool,
 }
 
 /// Response body from /api/read/{id}