6256 refactor messaging module to remove all provider specific code and put it inside the drivers folders (#6721)

Closes #6256 
Closes #6257 
+ Create custom exceptions

---------

Co-authored-by: Charles Bochet <charles@twenty.com>

packages/twenty-server/src/modules/messaging/message-import-manager/exceptions/message-import.exception.ts

@@ -0,0 +1,14 @@
+import { CustomException } from 'src/utils/custom-exception';
+
+export class MessageImportException extends CustomException {
+  code: MessageImportExceptionCode;
+  constructor(message: string, code: MessageImportExceptionCode) {
+    super(message, code);
+  }
+}
+
+export enum MessageImportExceptionCode {
+  UNKNOWN = 'UNKNOWN',
+  PROVIDER_NOT_SUPPORTED = 'PROVIDER_NOT_SUPPORTED',
+  MESSAGE_CHANNEL_NOT_FOUND = 'MESSAGE_CHANNEL_NOT_FOUND',
+}