Function prepare_raw 

pub fn prepare_raw<F>(
    entry: F,
    name: String,
    stack_size: usize,
) -> Result<PreparedThread, TaskError>
where
    F: FnOnce() + Send + 'static,

Creates a scheduler-owned kernel thread without making it runnable.

An OS publication transaction must call PreparedThread::stage before exposing external identity and StagedThread::activate after commit.