perf(smart-playlist): suggest rule values for what was typed

The rule editor's value box built its suggestions from libraryStore's
whole-library arrays, which made it one more reason to load every
track at startup, and left it empty when they had not loaded.

SuggestSmartPlaylistValues answers with up to 50 distinct values of a
field that contain the typed text, from the same joined row the rules
match against, so a suggestion is always something a rule can match.
yj-combobox announces its filter text so the editor can ask, debounced
and cached per field and text.

Refs #279

frontend/bindings/yellowjacket/backend/playlist/service.ts

@@ -309,6 +309,14 @@ export function SearchLibrary(query: string): $CancellablePromise<$models.Candid
     return $Call.ByID(3912116995, query);
 }
 
+/**
+ * SuggestSmartPlaylistValues returns values of field present in the
+ * library that contain needle, for the rule editor's value box.
+ */
+export function SuggestSmartPlaylistValues(field: string, needle: string): $CancellablePromise<string[] | null> {
+    return $Call.ByID(3718198115, field, needle);
+}
+
 /**
  * ToggleDefaultPlaylistTrack adds or removes a single track
  * from the default playlist.  Returns true if the track is now