[SailfishOS] Migrate config.yml file to Sailjail-assigned location

teertinker writes:

After your Releasenotes, I wanted to give Whisperfish a try. Everything seems to work properly (Registration, start a chat with a person from contacts). However, after closing Whisperfish, I have to start the registration procedure again. If I start Whisperfish from cli, it states Could not open config file: home/defaultuser/.config/harbour-whisperfish/config.yml

in .config only the folder harbour-file-browser exists.

This is due to still unfinished migration from pre-Sailjail era.