Dump additional metadata when converting openhands trajectories

[neubig]

Is it worth dumping the rest of the tool call metadata in here as well? There's some other useful info in there (model info, token counts) that might be nice to have available.

      // Add any tool metadata
      if (event.tool_call_metadata) {
        entry.metadata = {

Originally posted by @csmith49 in #2 (comment)