perplexity : add support for batch size to `--perplexity` (#407)

* Add support to batch size for perplexity

* Revert "Fix memory allocation issues and seg faults"

This reverts commit 4870e455b3653f7d7769fa5772b2c90ffad088df.

* update from merge

* Remove perplexity from main

* updates

* Update batch size for efficiency