All results are scored, we only process CodeCompletionStrings for the winners.
We now return CompletionList rather than CompletionItem[] (both are valid).
sortText is now based on CodeCompletionResult::orderedName (mostly the same).
This is the first clangd-only completion option, so plumbing changed.
It requires a small clangd patch (exposing CodeCompletionResult::orderedName).
(This can't usefully be enabled yet: we don't support server-side filtering)