Add the option to set a default page for browser tabs

Hi- I’m opening this thread for discussion surrounding the possibility of allowing the user to set a default page that should be opened in browser tabs. Personally, I’d set https://start.duckduckgo.com to be the default, but search engines are an incredibly opinionated thing, so I could understand having nothing as a default too.

Initially I figured that this wouldn’t need a discussion thread about it, but I noticed that there doesn’t appear to be any existing way to configure plugins in general (and the web browser tabs appear to be from a plugin), so there may need to be discussion surrounding how that should work.

I think it would be fairly simple to add preferences registered by plugins to be displayed underneath their metadata in the AdwExpanderRow, but that might not make it obvious that a plugin has options to configure or not.