feat: add support for bytedance's doubao (#1438)

* 增加豆包大模型支持

* chore: update channel options & add prompt

---------

Co-authored-by: 康龙彪 <longbiao.kang@i-tudou.com>
Co-authored-by: JustSong <songquanpeng@foxmail.com>

relay/adaptor/doubao/main.go

@@ -0,0 +1,14 @@
+package doubao
+
+import (
+	"fmt"
+	"github.com/songquanpeng/one-api/relay/meta"
+	"github.com/songquanpeng/one-api/relay/relaymode"
+)
+
+func GetRequestURL(meta *meta.Meta) (string, error) {
+	if meta.Mode == relaymode.ChatCompletions {
+		return fmt.Sprintf("%s/api/v3/chat/completions", meta.BaseURL), nil
+	}
+	return "", fmt.Errorf("unsupported relay mode %d for doubao", meta.Mode)
+}