feat(ui): change popup logic (#442)

## Summary

* refactors Indexing popups into ScreenComponents (they had different
implementations in different files)
* removes Indexing popup for small chapters
* only show Indexing popup (without progress bar) for large chapters
(using same minimum file size condition as for progress bar before)

## Additional Context

* Having to show even single popup message and redraw the screen slows
down the flow significantly
* Testing results:
    * Opening large chapter with progress bar - 11 seconds
* Same chapter without progress bar, only single Indexing popup - 5
seconds

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### AI Usage

Did you use AI tools to help write this code? _**< PARTIALLY>**_

src/activities/boot_sleep/SleepActivity.h

@@ -10,7 +10,6 @@ class SleepActivity final : public Activity {
   void onEnter() override;
 
  private:
-  void renderPopup(const char* message) const;
   void renderDefaultSleepScreen() const;
   void renderCustomSleepScreen() const;
   void renderCoverSleepScreen() const;