Added tool calling support (#731)

Co-authored-by: krut_ni <nils.kruthoff@dlr.de>
Co-authored-by: Thorsten Sommer <SommerEngineering@users.noreply.github.com>

app/MindWork AI Studio/Provider/OpenAI/AssistantToolCallMessage.cs

@@ -0,0 +1,16 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace AIStudio.Provider.OpenAI;
+
+public sealed record AssistantToolCallMessage : IMessageBase
+{
+    public string Role { get; init; } = "assistant";
+
+    public JsonElement? Content { get; init; }
+
+    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
+    public string? ReasoningContent { get; init; }
+
+    public IList<ChatCompletionToolCall> ToolCalls { get; init; } = [];
+}