Mobile: Hide advanced settings by default

[personalizedrefrigerator]

Summary

Hides advanced settings by default on mobile.

This is related to #9652:

• We may not want to display the "load plugin from file" button by default.
• Currently, the "load from file" button is directly below "Search"

Screen recording

out.mp4

Testing

1. Open settings
2. Open "synchronization"
3. Show advanced settings
4. Hide advanced settings
5. Search for "sync" and click "show advanced settings"

This has been manually tested on Android 7.

Notes

• react-native-paper is used to create a Button (rather than react-native) to simplify adding a "show"/"hide" icon.
  • This gives the button a ripple effect. As other buttons currently don't have this, I think I would rather not have this effect.