feat: support gemini-2.0-flash (#2055)

* feat: support gemini-2.0-flash

- Enhance model support by adding new entries and refining checks for system instruction compatibility.
- Update logging display behavior and adjust default quotas for better user experience.
- Revamp pricing structures in the billing system to reflect current model values and deprecate outdated entries.
- Streamline code by replacing hardcoded values with configurations for maintainability.

* feat: add new Gemini 2.0 flash models to adapter and billing ratio

* fix: update GetRequestURL to support gemini-1.5 model in versioning

relay/adaptor/gemini/adaptor.go

@@ -5,9 +5,10 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"strings"
 
 	"github.com/gin-gonic/gin"
-
+	"github.com/songquanpeng/one-api/common/config"
 	"github.com/songquanpeng/one-api/common/helper"
 	channelhelper "github.com/songquanpeng/one-api/relay/adaptor"
 	"github.com/songquanpeng/one-api/relay/adaptor/openai"
@@ -20,17 +21,12 @@ type Adaptor struct {
 }
 
 func (a *Adaptor) Init(meta *meta.Meta) {
-
 }
 
 func (a *Adaptor) GetRequestURL(meta *meta.Meta) (string, error) {
-	var defaultVersion string
-	switch meta.ActualModelName {
-	case "gemini-2.0-flash-exp",
-		"gemini-2.0-flash-thinking-exp",
-		"gemini-2.0-flash-thinking-exp-01-21":
-		defaultVersion = "v1beta"
-	default:
+	defaultVersion := config.GeminiVersion
+	if strings.Contains(meta.ActualModelName, "gemini-2.0") ||
+		strings.Contains(meta.ActualModelName, "gemini-1.5") {
 		defaultVersion = "v1beta"
 	}