chore: cleanup Altinn.Platform.Models

feat: enable nullable reference types in Altinn.Platform.Models BREAKING-CHANGE: This change enables nullable reference types in Altinn.Platform.Models. All reference types are set as nullable by default and is likely to cause consumers of this library to get compiler warnings where they previously did not. Eventually, some of these properties will be set as non-nullable. We do not consider this a breaking change.

feat: make lists in Altinn.Platform.Models IReadOnlyList<T> BREAKING-CHANGE: This change makes all lists in Altinn.Platform.Models IReadOnlyList<T> instead of List<T>. This is to enable us to change the implementation of these lists in the future without breaking consumers of the library. The list properties are still writable, so the entire list can be replaced if for some reason that is needed.

feat: make most types record Most types in Altinn.Platform.Models are now records. This mostly provides better ToString implementations. This affects how equality is determined for these types, but we do not consider this a breaking change.

chore: mark LanguageType in ProfileSettingPreference obsolte BREAKING-CHANGE: The LanguageType property in ProfileSettingPreference is marked obsolete. It is a set-only property which just proxies to the Language property and is only present for historical reasons. It will eventually be removed.

chore: make Altinn.Platform.Models target .net 8.0 BREAKING-CHANGE: Altinn.Platform.Models now targets .net 8.0. This means that consumers of this library must also target .net 8.0 or later.

Altinn / altinn-register

chore: cleanup Altinn.Platform.Models #255

Quality Gate passed