Ensure we have acceptable search engines

Epic: https://source.puri.sm/Librem5/use-cases/issues/51

GNOME Web aka Epiphany will likely be the default web browser, so we should ensure it comes with respectable search engines by default.

Pure Browser comes with DuckDuckGo by default and so does Web if I'm not mistaken, but it's worth ensuring it's the case.

Should we add more respectable browsers like:

• Qwant (the French equivalent to DDG, I personally prefer it over DDG)
• Ecosia
• Maybe some trustable Searx instance (even though the results tend to be subpar):
  • https://www.searx.me/
  • https://searx.org/
  • https://searx.laquadrature.net/
  • https://searx.aquilenet.fr/
  • https://tontonroger.org/

Maybe we could also drop Google from the search engines we ship.

• GNOME Web browser search shows Google/Bing
• Phone Essentials List