feat: 新增向量嵌入服务支持

新增SiliconFlow向量嵌入服务实现，支持文本向量化功能：
- 新增ITextEmbeddingService接口和SiliconFlowTextEmbeddingService实现
- 新增EmbeddingCreateRequest/Response等向量相关DTO
- 在AiGateWayManager中新增EmbeddingForStatisticsAsync方法
- 在OpenApiService中新增向量生成API接口
- 扩展ModelTypeEnum枚举支持Embedding类型
- 优化ThorChatMessage的Content属性处理逻辑

Yi.Abp.Net8/module/ai-hub/Yi.Framework.AiHub.Domain/AiGateWay/ITextEmbeddingService.cs

@@ -0,0 +1,19 @@
+using Yi.Framework.AiHub.Application.Contracts.Dtos.OpenAi.Embeddings;
+using Yi.Framework.AiHub.Domain.Shared.Dtos;
+
+namespace Yi.Framework.AiHub.Domain.AiGateWay;
+
+public interface ITextEmbeddingService
+{
+    /// <summary>
+    /// 
+    /// </summary>
+    /// <param name="createEmbeddingModel"></param>
+    /// <param name="aiModelDescribe"></param>
+    /// <param name="cancellationToken"></param>
+    /// <returns></returns>
+    Task<EmbeddingCreateResponse> EmbeddingAsync(
+        EmbeddingCreateRequest createEmbeddingModel,
+        AiModelDescribe? aiModelDescribe = null,
+        CancellationToken cancellationToken = default);
+}