[Configs] Add sequence_parallel_size and SequenceParallelSampler to configs

[HIT-cwh]

Modified configs: deepseek, llama2, internlm2, yi and zephyr.

1. Add sequence_parallel_size to configs
2. accumulative_counts = accumulative_counts * sequence_parallel_size. Suppose I aim to employ a training strategy using a batch size per device of 1 with a maximum length of max_length on N GPUs. Upon setting the sequence parallelism dimension to SP, the accumulative counts have to be adjusted to SP times the original value. This modification is essential to assure training equivalence, as the sequence of max_length length will be segmented into SP parts, with each part being allocated to its respective GPU among the SP GPUs for parallelized training.
3. If sequence_parallel_size is greater than 1, use SequenceParallelSampler, otherwise use DefaultSampler.