feat: add staff tax forms module with I-9 and W-4 forms

- Created staff_tax_forms_module.dart to manage tax forms feature.
- Implemented routes for TaxFormsPage, FormI9Page, and FormW4Page.
- Added mock repository for tax forms.
- Established necessary dependencies in pubspec.yaml.
- Exported module in staff_tax_forms.dart.

apps/mobile/pubspec.lock

@@ -1071,6 +1071,13 @@ packages:
       relative: true
     source: path
     version: "0.0.1"
+  staff_tax_forms:
+    dependency: transitive
+    description:
+      path: "packages/features/staff/profile_sections/compliance/tax_forms"
+      relative: true
+    source: path
+    version: "0.0.1"
   stream_channel:
     dependency: transitive
     description: