Function execute_server_flow 

pub fn execute_server_flow(
    ir: &IRProgram,
    flow_name: &str,
    backend: &str,
    source_file: &str,
    api_key_override: Option<&str>,
    request_body: Option<&Value>,
    request_path: &HashMap<String, String>,
    request_query: &HashMap<String, String>,
    tool_base_url: Option<&str>,
) -> Result<ServerRunnerMetrics, String>