Wizard: Add Users step to the wizard (HMS-4902)

This commit adds a new step 'Users' that is enabled only in stage-preview,
and will enable it in stage-stable once IQE tests are ready.
The step is not functional yet, this is just the first step.

src/test/setup.ts

@@ -53,6 +53,8 @@ vi.mock('@unleash/proxy-client-react', () => ({
   useUnleashContext: () => vi.fn(),
   useFlag: vi.fn((flag) => {
     switch (flag) {
+      case 'image-builder.users.enabled':
+        return true;
       case 'image-builder.import.enabled':
         return true;
       case 'image-builder.firstboot.enabled':