Allow a more selective restore of configuration

Today, the configuration restore is an all or nothing process. There is a need for the process to be more selective.

The configuration data can be broken down in to categories:

- Connections, schemas, previous sessions
- Custom styles
- App settings
- Layout settings

To keep things simple, we can restore each of these categories separately. And a restore would fully replace all contents of that category. So no merging of data, and therefore no conflict resolution.

No files, tests, or entry points are named in the issue. Start by locating the existing configuration restore flow and mapping its data to the four listed categories; done means each category can be restored independently and fully replaces that category without merging or conflict resolution.

Written by the indexing model from the issue text.