max_seq_len parameter for summarize_results

[Kipok]

we just merged #534 that adds an option to specify --max_seq_len parameter for summarize_results call. You can use it to get benchmark scores for different length thresholds, e.g. if you ran generation with 32k tokens, you can then do

ns summarize_results <output folder> --max_seq_len 8192

and see what scores you'd get if you only used 8192 tokens (anything longer than that is considered incorrect)