pub fn create_and_seek_to_key(table: Arc<SsTable>, key: KeySlice) -> Result<Self> {
        let (blk_idx, blk_iter) = Self::seek_to_key_inner(&table, key)?;
        let iter = Self {
            blk_iter,
            table,
            blk_idx,
        };
        Ok(iter)
    }
Create a new iterator and seek to the first key-value pair which >= `key`.
mini-lsm/src/table/iterator.rs