101 featch available variables from previous steps (#8062)

- add outputSchema in workflow step settings
- use outputSchemas to compute step available variables


https://github.com/user-attachments/assets/6b851d8e-625c-49ff-b29c-074cd86cbfee

packages/twenty-server/src/modules/workflow/workflow-trigger/types/workflow-trigger.type.ts

@@ -1,12 +1,19 @@
+import { OutputSchema } from 'src/modules/workflow/workflow-executor/types/workflow-step-settings.type';
+
 export enum WorkflowTriggerType {
   DATABASE_EVENT = 'DATABASE_EVENT',
   MANUAL = 'MANUAL',
 }
 
+type BaseWorkflowTriggerSettings = {
+  input?: object;
+  outputSchema: OutputSchema;
+};
+
 type BaseTrigger = {
   name: string;
   type: WorkflowTriggerType;
-  input?: object;
+  settings: BaseWorkflowTriggerSettings;
 };
 
 export type WorkflowDatabaseEventTrigger = BaseTrigger & {