Implement OpenAI chat completions in GO (#16177)

### What problem does this PR solve?

Implement OpenAI chat completions in GO

POST /api/v1/openai/<chat_id>/chat/completions

OpenAI chat cli: internal/development.md

### Type of change

- [x] Refactoring

internal/cli/parser.go

@@ -206,6 +206,8 @@ func (p *Parser) parseUserCommand() (*Command, error) {
 		return p.parseStreamCommand()
 	case TokenChat:
 		return p.parseChatCommand()
+	case TokenOpenaiChat:
+		return p.parseOpenaiChatCommand()
 	case TokenThink:
 		return p.parseThinkCommand()
 	case TokenEmbed: