Provide a lot more search engines for default search engine preference

[bbondy]

We can get the list from Chrome's settings:

Also we can support a simpler format than having to parse the open search xml formats. We should leave support for open search xml too though.
#790

[thepup]

Just looked through all the supoort tickets that mentioned search engines, and here are the one's that were requested:

1. startpage.com
2. bing.com
3. ecosia.org
4. qwant.com
5. yahoo.com
6. wikipedia.org

I'll add any new ones that come up periodically.

[bsclifton]

Besides having support for a good number of search engines, we should allow the user to edit or delete the existing search engines

[bsclifton]

Tentatively assigned this to 1.1.0 milestone after seeing comment in #3053

cc: @bradleyrichter

[da2x]

See my comment here for a method for automatically adding the user's favorite search engines. I think that approach is better than bundling 100 search engines by default.

[luixxiul]

I think this can be closed because the requests for adding search engines have been made in other tickets like #2701 and #2703, and this seems to track nothing specific.

[bsclifton]

@luixxiul I agree- as long as the other requests for search engines are labelled with feature/search, we should be good to go 😄 The user-editable one (which includes the suggestion by @da2x) can be found here #3053