Improve UNINSTALL logic

[robinjhuang]

Add custom uninstall logic to Windows NSIS:

1. Should delete the extra_model_config.yaml file. This is always saved to app.getPath('userData').

Bonus: Read the file and the python environment located at "base_path". For example, it should delete everything under /Users/junhanhuang/Documents/ComfyUI/.venv and /Users/junhanhuang/Documents/ComfyUI/uv-cache

eg.

# ComfyUI extra_model_paths.yaml for darwin
comfyui:
  base_path: /Users/junhanhuang/Documents/ComfyUI
  is_default: true
  checkpoints: models/checkpoints/
  classifiers: models/classifiers/
  clip: models/clip/
  clip_vision: models/clip_vision/
  configs: models/configs/
  controlnet: models/controlnet/
  diffusers: models/diffusers/
  diffusion_models: models/diffusion_models/
  embeddings: models/embeddings/
  gligen: models/gligen/
  hypernetworks: models/hypernetworks/
  loras: models/loras/
  photomaker: models/photomaker/
  style_models: models/style_models/
  unet: models/unet/
  upscale_models: models/upscale_models/
  vae: models/vae/
  vae_approx: models/vae_approx/
  custom_nodes: custom_nodes/

A development script that does this already exists in: 8e55f55

[robinjhuang]

From Dave:

Yes, you can add something like this:
!macro customUnInstall
ExecWait "del /f C:\Some\Path"
!macroend
https://www.npmjs.com/package/@todesktop/cli#windowsnsisinclude---optional-string

[robinjhuang]

Can we encompass this logic as a function that we can expose in the Electron API as "resetInstall" command?

Needed in: rg/electron/issues/270

We want to add this as a button you can click when an error occurs...

[robinjhuang]

#279