Add non-gui support

[bendavis78]

It would nice if this could be run as a cmdline, or even better make it a separate python lib w/ cmdline support.

[niknah]

This GUI is an overkill for doing something simple.
Different model files may rearrange the keys differently, here are some examples...
https://gist.github.com/Tumppi066/42482956139d79cb7c05e0b8f3cfef69
https://huggingface.co/niknah/Hunyuan3D-2.1-safetensors/blob/main/ckpt2safetensors.py