feat(gemini): implement video generation configuration and billing estimation

- Added Gemini video generation configuration structures and payloads.
- Introduced functions for parsing and resolving video duration and resolution from metadata.
- Enhanced the Vertex adaptor to support Gemini video generation requests and billing estimation based on duration and resolution.
- Updated model pricing settings for new Gemini video models.

dto/openai_video.go

@@ -43,6 +43,7 @@ func (m *OpenAIVideo) SetMetadata(k string, v any) {
 func NewOpenAIVideo() *OpenAIVideo {
 	return &OpenAIVideo{
 		Object: "video",
+		Status: VideoStatusQueued,
 	}
 }