[Feature Request]: Dynamically change input and widget position

### 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 ?

I want to add an input and/or a widget at a custom place and not at the end. I also want to be able to resort the input and widget position (a simple swap would help to keep things simple)

Reason: I'm creating a `if/then/elif/.../else` custom node. So I need to be able to add a `elif_123` and `then_123` widget and input at the corresponding places in the list.

### Proposed workflow

Implement a `input_swap(indexA, indexB)` and/or `widget_swap(indexA, indexB)` method to the ComfyNode class.

### Additional information

_No response_

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-3957-Feature-Request-Dynamically-change-input-and-widget-position-1fa6d73d3650818991b4db6914b92891) by [Unito](https://www.unito.io)