Allow Privacy Focused POST Search Engines

[Exitium-DEV]

Vanadium discovers any website that follows the Open search GET specification to the degree of checking if the URL contains ?q=%s as params, but has zero support for the widely growing privacy focused search engines which use POST (SearXNG, DuckDuckGo to name a few)

With GrapheneOS being privacy focused, I believe it would be a welcome feature to have, and would require little work to implement in comparison to other feature requests. Almost like an 'easy win'.

For those that don't understand how this helps with privacy - your search history doesnt log the URL, in conjunction with ommiting tje search term from page title, your web history means nothing if you have it logging, even for a brief time before deletion.

Thank you!