main : add option to save full output to session (#1338)

* main : add option to save full output to session

* split behavior into --session and --prompt-cache

* restore original implementation with new names

* PR comments

* move the check for incompatible parameters to gpt_params_parse

* Fix whitespace

Co-authored-by: DannyDaemonic <DannyDaemonic@gmail.com>

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Co-authored-by: DannyDaemonic <DannyDaemonic@gmail.com>