Clean up OrchestratorLogin dialog, settings and config.json

[jackjansen]

This isn't really relevant until we have allowed storing all settings locally, i.e. outside of the orchestrator.

We need three levels of settings:

• builtin, from VRTInitializer in LoginManager scene
• overrides from config.json
• more overrides from configoverride.json

If we want to allow saving configoverride.json it should be from a separate dialog, probably.

[jackjansen]

Forget about configoverride.json. In stead we will store the items that are "classically" kept in the orchestrator (the user settings) in a separate config file.

[jackjansen]

This issue is pretty much outdated.