Problem deserializing one Kontent element into multiple properties of different types

[petrsvihlik]

Brief bug description

Originally submitted by @Enngage: When deserializing one Kontent element into multiple properties of different types, only the first type gets resolved correctly.

Repro steps

public IRichTextContent Description { get; set; }

 [JsonProperty("description")]
public string DescriptionString { get; set; }

When these two properties are included in a single model, DescriptionString won't get resolved. If you put the JsonPropertyAttribute to the other property, the IRichTextContent won't get resolved.

Expected behavior

Both properties should get resolved correctly.

Additional context

The problem is with caching the resolved properties. The fix should be relatively simple - just extend the caching key of
the processedItems collection by adding the target property type.

Sample occurrence:
https://github.com/Kentico/kontent-delivery-sdk-net/blob/38de66829a7d1cc07bddbffc3febbf29f33788bd/Kentico.Kontent.Delivery/ContentItems/ModelProvider.cs#L169

Make sure all occurrences of processedItems in the ModelProvider are covered.