1750 extensibility twenty sdk v2 use twenty sdk to define an object (#15230)

We maintain jsonc object definition but will deprecate them pretty soon

## Before
<img width="1512" height="575" alt="image"
src="https://github.com/user-attachments/assets/d2fa6ca4-c456-4aa9-a1e3-845b61839718"
/>

## After
<img width="1260" height="555" alt="image"
src="https://github.com/user-attachments/assets/ba72f4cf-d443-4967-913c-029bc71f3f48"
/>

packages/twenty-cli/src/utils/__tests__/get-decorated-class.spec.ts

@@ -0,0 +1,21 @@
+import { getDecoratedClass } from '../../utils/get-decorated-class';
+
+describe('getDecoratedClass', () => {
+  it('should return properly formatted class', () => {
+    const result = getDecoratedClass({
+      data: { nameSingular: 'Name', namePlural: 'Names' },
+      name: 'MyNewObject',
+    });
+
+    const expectedResult = `import { ObjectMetadata } from 'twenty-sdk';
+
+@ObjectMetadata({
+  nameSingular: 'Name',
+  namePlural: 'Names',
+})
+export class MyNewObject {}
+`;
+
+    expect(result).toEqual(expectedResult);
+  });
+});