Make MaskinportenSettingsconfiguration path configurable

[danielskovli]

Description

The configuration name for the MaskinportenSettings object is currently hardcoded at "MaskinportenSettings" in AddMaskinportenClient. Vi have the ability to override this via the ConfigureMaskinportenClient method, but this is perhaps a bit heavy handed in some situations.

Some service owners have many apps running in the same cluster, with the same KeyVault, but require each app to have their own Maskinporten client setup. Which means that the KeyVault entries and appsettings.json configurations are typically prefixed with a unique string (often the app name).

Eg:

appsettings.json

"appname-MaskinportenSettings": {
    "authority": "https://test.maskinporten.no/",
    "clientId": "",
    "jwkBase64": ""
}

keyvault

appname-MaskinportenSettings--ClientId = xxx
appname-MaskinportenSettings--EncodedJwk = xxx

It would be optimal if we could support an app binding to appname-MaskinportenSettings instead of the default hardcoded value.

The manual config done through ConfigureMaskinportenClient can possibly service this purpose, but moves a lot of the configuration out of appsettings.json and in to the codebase itself. Unless there are clever patterns available there to inject values as needed.

Proposed implementation

Create a public method ServiceCollectionExtensions.ConfigureMaskinportenClient that takes a string parameter to pass to IServiceCollection.BindConfiguration.

Calling this method before services.AddAltinnAppServices in Program.cs will result in ServiceCollectionExtensions.AddMaskinportenClient using the newly provided configuration binding instead of the default MaskinportenSettings.