Hide cursors with non-empty selection if showCursorsOnSelection is false

Also, remove some barely used public APIs around cursor visibility that
don't make much sense and are not ideal for performance. We don't want
to subscribe to the visibility of each cursor.

src/text-editor.coffee

@@ -379,7 +379,7 @@ class TextEditor extends Model
         when 'showCursorOnSelection'
           if value isnt @showCursorOnSelection
             @showCursorOnSelection = value
-            cursor.setShowCursorOnSelection(value) for cursor in @getCursors()
+            @component?.scheduleUpdate()
 
         else
           if param isnt 'ref' and param isnt 'key'