Additional cleanup after libgemma refactor https://github.com/google/gemma.cpp/pull/82

[austinvhuang]

Will retarget this PR to dev once the examples branch PR merges to dev. #82 already was already large enough, these changes are left as a follow-up for now.

• Move command line argument definitions out of the gemma.h interface (to app.h)
• Fix off-by-1 printing of "." for prefill tokens
• Update libgemma commit hash for hello_world

[pculliton]

LGTM.

[Zeenat30]

[Zeenat30]

Now this is facts theft is theft ask permission at least I was working on another project with my api

[jan-wassenberg]

I see a screenshot that appears to have nothing to do with this Gemma.cpp repository. Further such comments will be reported and deleted.