feat: refactor token estimation logic

- Introduced new OpenAI text models in `common/model.go`.
- Added `IsOpenAITextModel` function to check for OpenAI text models.
- Refactored token estimation methods across various channels to use estimated prompt tokens instead of direct prompt token counts.
- Updated related functions and structures to accommodate the new token estimation approach, enhancing overall token management.

relay/channel/openai/relay-openai.go

@@ -183,7 +183,7 @@ func OaiStreamHandler(c *gin.Context, info *relaycommon.RelayInfo, resp *http.Re
 	}
 
 	if !containStreamUsage {
-		usage = service.ResponseText2Usage(c, responseTextBuilder.String(), info.UpstreamModelName, info.PromptTokens)
+		usage = service.ResponseText2Usage(c, responseTextBuilder.String(), info.UpstreamModelName, info.GetEstimatePromptTokens())
 		usage.CompletionTokens += toolCount * 7
 	}
 
@@ -245,9 +245,9 @@ func OpenaiHandler(c *gin.Context, info *relaycommon.RelayInfo, resp *http.Respo
 			}
 		}
 		simpleResponse.Usage = dto.Usage{
-			PromptTokens:     info.PromptTokens,
+			PromptTokens:     info.GetEstimatePromptTokens(),
 			CompletionTokens: completionTokens,
-			TotalTokens:      info.PromptTokens + completionTokens,
+			TotalTokens:      info.GetEstimatePromptTokens() + completionTokens,
 		}
 		usageModified = true
 	}
@@ -336,8 +336,8 @@ func OpenaiTTSHandler(c *gin.Context, resp *http.Response, info *relaycommon.Rel
 	// and can be terminated directly.
 	defer service.CloseResponseBodyGracefully(resp)
 	usage := &dto.Usage{}
-	usage.PromptTokens = info.PromptTokens
-	usage.TotalTokens = info.PromptTokens
+	usage.PromptTokens = info.GetEstimatePromptTokens()
+	usage.TotalTokens = info.GetEstimatePromptTokens()
 	for k, v := range resp.Header {
 		c.Writer.Header().Set(k, v[0])
 	}
@@ -383,7 +383,7 @@ func OpenaiSTTHandler(c *gin.Context, resp *http.Response, info *relaycommon.Rel
 	}
 
 	usage := &dto.Usage{}
-	usage.PromptTokens = info.PromptTokens
+	usage.PromptTokens = info.GetEstimatePromptTokens()
 	usage.CompletionTokens = 0
 	usage.TotalTokens = usage.PromptTokens + usage.CompletionTokens
 	return nil, usage