Let SettingsMapper create objects directly

[hanneskod]

Using an interface like

public function getOrganizationName(): string;
public function getOrganizationId(): StateId;
public function getBankgiro(): Bankgiro;
public function getBgcCustomerNumber(): string;

Creates a single entry point for factories, and a great place for error checking and throwing informative exceptions...

[hanneskod]

Some doubts here. Why not let settings go in a simple giroapp.json settings file. Then create a wrapper with the factory stuff..

The drawback is that we may or may not have init.

The gain is a simpler interface for plugins to add specific settings, and for users to tweek plugins..

[hanneskod]

Related to #152

[hanneskod]

outdated..