[Feature Request]: When downloading missing model, add better indication of what the correct directory is

### Is there an existing issue for this?

- [x] I have searched the existing issues and checked the recent builds/commits

### What would your feature do ?

Add better indication of where a model should be downloaded in the missing models dialog:


It may not be obvious what the correct location is or that it will only work if the correct location is chosen, especially if this happens during your first time using ComfyUI.

Currently the parent directory is shown, but the absolute location is not obvious and it is also possibly not obvious that this refers to a directory name and just a category name.

### Proposed workflow

1. A workflow is loaded with a model field
2. The user does not have the model downloaded
3. The missing models dialog appears, asking if they want to download
4. The user clicks the download button
5. **-- add some mechanism to indicate that this will only work if you download to a particular folder --**
6. The native file explorer window appears, and the user selects the correct location

### Additional information

The correct directory is already included in the workflow `moddel` field:

```json
"models": [
{
"name": "flux1-schnell-fp8.safetensors",
"url": "https://huggingface.co/Comfy-Org/flux1-schnell/resolve/main/flux1-schnell-fp8.safetensors?download=true",
"directory": "checkpoints"
}
],
```

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-2353-Feature-Request-When-downloading-missing-model-add-better-indication-of-what-the-c-1876d73d36508135bec4f01287a896ba) by [Unito](https://www.unito.io)