Add support of ChatGPT extensions

[JulyIghor]

It would be great if you could add an option to use multiple ChatGPT icons, and for each icon, add an option to define a startup command. This would work similarly to the "My ChatGPT" feature. So we can set something like "Fix English message if needed, no commentary". We will have a separate button to modify the selected text using a specific task.

[pilotmoon]

Fully agree, I have been dragging my feet on adding this