Move convert.py to examples/convert-legacy-llama.py (#7430)

* Move convert.py to examples/convert-no-torch.py

* Fix CI, scripts, readme files

* convert-no-torch -> convert-legacy-llama

* Move vocab thing to vocab.py

* Fix convert-no-torch -> convert-legacy-llama

* Fix lost convert.py in ci/run.sh

* Fix imports

* Fix gguf not imported correctly

* Fix flake8 complaints

* Fix check-requirements.sh

* Get rid of ADDED_TOKENS_FILE, FAST_TOKENIZER_FILE

* Review fixes