Show notation codes in autocomplete list

[osma]

Searching with notation codes (#456) now works, but the autocomplete box doesn't show the matched notation code, which can be confusing:

The notation code should be shown next to the label, as is done in other places in the UI.

Open questions:

1. Should the notation codes always be shown in the autocomplete, or only when the match was made based on notation code?
2. If notation codes should always be shown, there are two options:
   a) Add a notation field to the results of the REST search method
   b) Don't change the REST API, but when performing the autocomplete search from JS code, set fields=notation