Restores the '/controlnet/control_types' API endpoint, which is immensely useful for anyone using ControlNet via the API
## Description
I recently opened an Issue on the main ControlNet extension repo Mikubill/sd-webui-controlnet#2737 suggesting that they add a new API endpoint to allow users to retrieve filtered data based on a Control Type, just like in the UI.
I was both shocked and immensely disappointed when they finally replied, stating that the endpoint does already exist!
I understand that Forge is a massive overhaul to A1111, so perhaps this aspect was removed to get everything working, and then just never reimplemented.
Whatever the case, this endpoint is truly amazing for using ControlNet via API. With only the 'models' and 'modules' endpoints, how the heck is someone to make a dynamic script? They would essentially have to take a fat chunk of existing ControlNet code, plus these few added functions, just to filter the data appropriately.
I'm an amateur coder, at best, however I'm quite confident about this implementation.
This uses your existing functions as best as possible, I believe, including your filter list and the check for currently loaded SD model version.
Please merge this.
Thank you
## Screenshots/videos:
<img width="1136" alt="Restored" src="https://github.com/lllyasviel/stable-diffusion-webui-forge/assets/1613484/8996c3f2-27be-4405-b0cd-7f05f3eaa2d2">
[response_1714160176770.json](https://github.com/lllyasviel/stable-diffusion-webui-forge/files/15134692/response_1714160176770.json)
## Checklist:
- [X] I have read [contributing wiki page](https://github.com/AUTOMATIC1111/stable-diffusion-webui/wiki/Contributing)
- [X] I have performed a self-review of my own code
- [X] My code follows the [style guidelines](https://github.com/AUTOMATIC1111/stable-diffusion-webui/wiki/Contributing#code-style)
- [X] My code passes [tests](https://github.com/AUTOMATIC1111/stable-diffusion-webui/wiki/Tests)
This tab has been broken since 6 months ago and no one even creates an issue for it ; this indicates no one uses it.
Also just tried original webui Train tab and it seems also broken even in Auto's repo.
so we remove it to make room for new tabs and new features.
Technically Correct Implementation of CLIP skip for all models.
Automatic1111 uses a weird logic to ignore SDXL clip skip but added an option to only set CLIP-L Skip with an offset 1, which means if one set skip as 3, then the SDXL CLIP G does not skip but SDXL CLIP L uses 3-1=2 as skip (not 3?!)
Forge now uses technically correct and consistent clip skip for all models. Forge now outweigh technical correctness over reproducing Auto results.
But one can get same results by just do not set clip skip for SDXL.
