Re-implements return first option

Since we get all the results quickly now, this aggregates all the
results that came back and sorts them by confidence, and returns the
highest confidence result. The confidences aren't great on free text
search, but conceptually that's how it should work at least.

It may make sense to aggregate the search results in all contexts, but
I'll propose that in a separate PR.

bookwyrm/book_search.py

@@ -148,8 +148,8 @@ class SearchResult:
 
     def __repr__(self):
         # pylint: disable=consider-using-f-string
-        return "<SearchResult key={!r} title={!r} author={!r}>".format(
-            self.key, self.title, self.author
+        return "<SearchResult key={!r} title={!r} author={!r} confidence={!r}>".format(
+            self.key, self.title, self.author, self.confidence
         )
 
     def json(self):