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/engine/utils/generate-fake-value.ts

@@ -0,0 +1,33 @@
+export const generateFakeValue = (valueType: string): any => {
+  if (valueType === 'string') {
+    return 'generated-string-value';
+  } else if (valueType === 'number') {
+    return 1;
+  } else if (valueType === 'boolean') {
+    return true;
+  } else if (valueType === 'Date') {
+    return new Date();
+  } else if (valueType.endsWith('[]')) {
+    const elementType = valueType.replace('[]', '');
+
+    return Array.from({ length: 3 }, () => generateFakeValue(elementType));
+  } else if (valueType.startsWith('{') && valueType.endsWith('}')) {
+    const objData: Record<string, any> = {};
+
+    const properties = valueType
+      .slice(1, -1)
+      .split(';')
+      .map((p) => p.trim())
+      .filter((p) => p);
+
+    properties.forEach((property) => {
+      const [key, valueType] = property.split(':').map((s) => s.trim());
+
+      objData[key] = generateFakeValue(valueType);
+    });
+
+    return objData;
+  } else {
+    return 'generated-string-value';
+  }
+};