Fix variable dropdown (#8521)

- fixed dropdown width
- add icons
- handle composite fields
## After

![image](https://github.com/user-attachments/assets/b9ac585e-2a39-4ab2-8620-739f83272b9b)

![image](https://github.com/user-attachments/assets/d9f7eabb-5693-4c1c-b81c-45a901479042)

![image](https://github.com/user-attachments/assets/9edced28-8a04-4951-913d-3e5561d4fcbe)

packages/twenty-server/src/engine/utils/generate-fake-value.ts

@@ -1,4 +1,12 @@
-export const generateFakeValue = (valueType: string): any => {
+type FakeValueTypes =
+  | string
+  | number
+  | boolean
+  | Date
+  | FakeValueTypes[]
+  | { [key: string]: FakeValueTypes };
+
+export const generateFakeValue = (valueType: string): FakeValueTypes => {
   if (valueType === 'string') {
     return 'generated-string-value';
   } else if (valueType === 'number') {