Add compare_id tests

app/soapbox/__tests__/compare_id.test.ts

@@ -0,0 +1,7 @@
+import compareId from '../compare_id';
+
+test('compareId', () => {
+  expect(compareId('3', '3')).toBe(0);
+  expect(compareId('10', '1')).toBe(1);
+  expect(compareId('99', '100')).toBe(-1);
+});