Check if we can force a web search on a specific set of sites

[RomainVialard]

Currently we can allow ChatGPTApp to perform a global web search using:
chat.enableBrowsing(true);
And we can restrict that web search to all pages of a given website:
ChatGPTApp.restrictToWebsite("https://support.google.com");

Might also be useful to allow web search on a list of websites.
Maybe simply by allowing the user to enter the ID of his own custom search engine.
https://programmablesearchengine.google.com/