feat(trigger): enhance trigger subscription handling with credential support

- Added `credentials` and `credential_type` parameters to various methods in `PluginTriggerManager`, `PluginTriggerProviderController`, and `TriggerManager` to support improved credential management for trigger subscriptions.
- Updated the `Subscription` model to include `parameters` for better subscription data handling.
- Refactored related services to accommodate the new credential handling, ensuring consistency across the trigger workflow.

api/core/trigger/entities/entities.py

@@ -173,6 +173,7 @@ class Subscription(BaseModel):
     )
 
     endpoint: str = Field(..., description="The webhook endpoint URL allocated by Dify for receiving events")
+    parameters: Mapping[str, Any] = Field(default={}, description="The parameters of the subscription constructor")
     properties: Mapping[str, Any] = Field(
         ..., description="Subscription data containing all properties and provider-specific information"
     )