Tb78: Restore does not load some general / layout settings

[RealRaven2000]

When restoring a backup, many settings are still not restored - this is a regression that has been introduced by the rewrite of preferences settings for Thunderbird 78. May also affect thunderbird 68 users (to be tested).

I noticed this today when I saw that palette types from a config file were not restored.

[RealRaven2000]

Also noticed that the setting from the Current Folder background dropdown selection are not stored (and cannot be restored)

this is because the preference extensions.quickfolders.currentFolderBar.background.selection is not directly bound to the UI element.

[RealRaven2000]

Fixed in 5.4 - Released 18/03/2021