SerializationService

[StefanGreve]

Subtask 1

• Fix release build error: serialization and deserialization requires a JsonSerializerContext when trimming is enabled.
• Add a minimal working example in the documentation

Subtask 2

• Define ISerializationService and add doc strings
• Implement SerializationService
• Implement AddSerializationService
• Publish a new version of AdvancedSystems.Core.Abstractions
• Write unit tests for SerializationService and AddSerializationService

Subtask 3

• Refactor CachingService and use SerializationService instead
• Register SerializationService in AddCachingService as scoped service
• Update unit tests (CachingServiceFixture, CachingServiceTests)

[StefanGreve]

Two things:

1. Turns out it is not possible to mock service methods that use stack-types in their method signature (see also: https://github.com/orgs/Advanced-Systems/discussions/2)
2. Making CachingService dependent on SerializationService may sound nice in theory, but is actually much harder to test due to the aforementioned reason, but also because I don't see a straightforward way to use Returns with Setup and a generic method signature.

For instance, this [1] doesn't work:

this.SerializationService
            .Setup(s => s.Serialize(It.IsAny<It.IsAnyType>(), It.IsAny<JsonTypeInfo<It.IsAnyType>>()))
            .Returns((object value, JsonTypeInfo<object> typeInfo) =>
            {
                return ObjectSerializer.Serialize(value, typeInfo).ToArray();
            });

Class fixture type 'AdvancedSystems.Core.Tests.Fixtures.CachingServiceFixture' threw in its constructor
---- System.ArgumentException : Invalid callback. Setup on method with parameters (byte[], JsonTypeInfo<It.IsAnyType>) cannot invoke callback with parameters (byte[], JsonTypeInfo).

[1] https://docs.educationsmediagroup.com/unit-testing-csharp/moq/generic-methods