🔧 [Lang API] Track what if the chat chunk is the final one

[roma-glushko]

Expose the status of the chunk in the stream: if it's the final chunk that closed the whole stream or not:

glide/pkg/providers/openai/chat_stream.go

Lines 114 to 133 in 6960732

	// TODO: use objectpool here
	chatResponse := schemas.ChatResponse{
	ID: completionChunk.ID,
	Created: completionChunk.Created,
	Provider: providerName,
	Cached: false,
	ModelName: completionChunk.ModelName,
	ModelResponse: schemas.ModelResponse{
	SystemID: map[string]string{
	"system_fingerprint": completionChunk.SystemFingerprint,
	},
	Message: schemas.ChatMessage{
	Role: completionChunk.Choices[0].Delta.Role,
	Content: completionChunk.Choices[0].Delta.Content,
	},
	},
	// TODO: Pass info if this is the final message
	}
	responseC <- chatResponse