Show the number of cards added in NoteEditorFragment

[lukstbit]

Purpose / Description

From #19194, Anki 25.09 changed addNote() to also return the number of cards so we can now show this to the user.

Before/After:

How Has This Been Tested?

Checked adding different number of cards when saving in NoteEditorFragment.

Checklist

• You have a descriptive commit message with a short title (first line, max 50 chars).
• You have commented your code, particularly in hard-to-understand areas
• You have performed a self-review of your own code
• UI changes: include screenshots of all affected screens (in particular showing any new or changed strings)
• UI Changes: You have tested your change using the Google Accessibility Scanner