typeahead: Treat query and source string in the same way before matching.

Like the source string, now the query too is converted into lower case
and has diacritics removed, before trying to determine a match.

web/shared/src/typeahead.ts

@@ -62,6 +62,9 @@ export function query_matches_string(
     source_str = source_str.toLowerCase();
     source_str = remove_diacritics(source_str);
 
+    query = query.toLowerCase();
+    query = remove_diacritics(query);
+
     if (!query.includes(split_char)) {
         // If query is a single token (doesn't contain a separator),
         // the match can be anywhere in the string.