refactor: enhance Evoai integration with improved validation and message handling

This commit refines the Evoai integration by updating the service and controller logic for better functionality and maintainability. Key changes include:
- Added the `openaiService` as a parameter in the EvoaiService constructor for improved dependency management.
- Enhanced the createBot method in EvoaiController to include EvoAI-specific validation and duplicate checks.
- Updated EvoaiDto and EvoaiSettingDto to remove unnecessary comments and add a fallback property.
- Refined the message processing logic in EvoaiService to handle audio messages more effectively and improve logging clarity.
- Adjusted the schema for Evoai settings to rename `evoaiIdFallback` to `botIdFallback` for better clarity.

These updates contribute to a more robust and maintainable Evoai integration.

src/api/integrations/chatbot/evoai/dto/evoai.dto.ts

@@ -1,11 +1,10 @@
 import { BaseChatbotDto, BaseChatbotSettingDto } from '../../base-chatbot.dto';
 
 export class EvoaiDto extends BaseChatbotDto {
-  // Evoai specific fields
   agentUrl?: string;
   apiKey?: string;
 }
 
 export class EvoaiSettingDto extends BaseChatbotSettingDto {
-  // Evoai specific fields
+  evoaiIdFallback?: string;
 }