Feat/support sendgrid (#21011)

Co-authored-by: André de Matteo <andre.matteo@accenture.com>
Co-authored-by: crazywoola <100913391+crazywoola@users.noreply.github.com>

api/extensions/ext_mail.py

@@ -54,6 +54,15 @@ class Mail:
                     use_tls=dify_config.SMTP_USE_TLS,
                     opportunistic_tls=dify_config.SMTP_OPPORTUNISTIC_TLS,
                 )
+            case "sendgrid":
+                from libs.sendgrid import SendGridClient
+
+                if not dify_config.SENDGRID_API_KEY:
+                    raise ValueError("SENDGRID_API_KEY is required for SendGrid mail type")
+
+                self._client = SendGridClient(
+                    sendgrid_api_key=dify_config.SENDGRID_API_KEY, _from=dify_config.MAIL_DEFAULT_SEND_FROM or ""
+                )
             case _:
                 raise ValueError("Unsupported mail type {}".format(mail_type))