keyboard: Fix updating suggestions visibility

Commit 237ba24dbe added corresponding API to the keyboard actor,
but ended up calling it on the KeyboardManager.

Add the expected method to KeyboardManager that forwards the request
to the keyboard.

https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/5630

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2359>

js/ui/keyboard.js

@@ -1276,6 +1276,10 @@ var KeyboardManager = class KeyBoardManager {
             this._keyboard.resetSuggestions();
     }
 
+    setSuggestionsVisible(visible) {
+        this._keyboard?.setSuggestionsVisible(visible);
+    }
+
     maybeHandleEvent(event) {
         if (!this._keyboard)
             return false;