Changes to some preference are not remembered

[per1234]

Describe the bug

File > Preferences opens a dialog where the user can set various preferences.

🐛 Changes to some of the preferences have no effect on the IDE and the changes are gone when the dialog is opened again.

To Reproduce

1. Select File > Preferences... from the Arduino IDE menus.
2. Check the box next to "☐ Show files inside Sketches.
3. Click the OK button.
4. Open the Sketchbook view.
   🐛 Files inside sketches are not shown.
5. Select File > Preferences... from the Arduino IDE menus.
   🐛 The box next to "☐ Show files inside Sketches is not checked.

Expected behavior

Changes to preferences are recognized and persistent.

Desktop

• OS: Windows 10
• Version: 2.0.0-rc3-snapshot-2f9bf86
  Date: 2022-02-11T14:52:06.341Z
  CLI Version: 0.21.0 [10107d24]

Additional context

I bisected the bug to 112153f (it does not occur in the build from the previous commit 69ac1f4).

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All the following preferences are affected:

• Show files inside Sketches
• Editor font size
• Interface scale > Automatic/%
• Language
• Show verbose output during > compile/upload
• Compiler warnings
• Verify code after upload

Changes to the other preferences are recognized.