Settings: Copy settings does not handle list of lists of submodels

[martastain]

Story

Deeply nested trees of settings are not copied properly, the event log is filled with warnings:

To reproduce

Steps to reproduce the behavior:

1. Use application addon, create different variants of blender application
2. Try to copy the settings to a newer addon version
3. Variants overrides are missing

Environment

• Server version: 1.1.1