Add support for Chat GPT/ChatGPT engine

[ngosang]

Working URL to the engine
You have to register but it's free with unlimited number of requests.
https://openai.com/blog/chatgpt/

Why do you want to add this engine?
It's not a search engine but it could provide really good answers. In many cases it's better than Google.

• https://threadreaderapp.com/thread/1598021488795586561.html
• https://dataconomy.com/2022/12/openai-chatgpt-chatbot-examples-limitations/
• https://www.engraved.blog/building-a-virtual-machine-inside/

Features of this engine
It's an AI / Machine learning model trained with a large corpus.

How can SearXNG fetch the information from this engine?

Applicable category of this engine

Additional context

Cross ref searxng/searxng#2008

[ngosang]

There is an experimental implementation here => searxng/searxng#2008 (comment)