models : make all scripts to be POSIX Compliant (#1725)

models : make all scripts to be POSIX Compliant (#1725)

* download-coreml-model: make it POSIX-compliant

* download-ggml-model: posix compliant (2nd)

* minor edit

* forgot to add newline

* generate-coreml-interface: far more straightforward

* generate-coreml-model: done with the posix thingy

* typo

* Update download-ggml-model.sh

* fix

* fix typo

* another fix

* Update download-coreml-model.sh

* Update download-ggml-model.sh

* Update download-coreml-model.sh