Add unit tests for imported products

Added unit tests for the imported_* products: both the create_imported_* and import_* workflows are now tested, and the fixtures have been updated so these kinds of products can now also be used in other tests.

Test coverage up from ~80% to 92%

test/workflows/site/test_create_imported_site.py

+import pytest
+from orchestrator.types import SubscriptionLifecycle
+from products.product_blocks.site import SiteTier
+
+from gso.products.product_types.site import ImportedSite
+from test.workflows import assert_complete, extract_state, run_workflow
+
+
+@pytest.mark.workflow()
+def test_create_imported_site_success(faker):
+    initial_created_site_data = [
+        {
+            "site_name": faker.site_name(),
+            "site_city": faker.city(),
+            "site_country": faker.country(),
+            "site_country_code": faker.country_code(),
+            "site_latitude": "-74.0060",
+            "site_longitude": "40.7128",
+            "site_bgp_community_id": faker.pyint(),
+            "site_internal_id": faker.pyint(),
+            "site_tier": SiteTier.TIER1,
+            "site_ts_address": faker.ipv4(),
+            "partner": "GEANT",
+        }
+    ]
+    result, _, _ = run_workflow("create_imported_site", initial_created_site_data)
+
+    assert_complete(result)
+    state = extract_state(result)
+    subscription_id = state["subscription_id"]
+    subscription = ImportedSite.from_subscription(subscription_id)
+    assert subscription.status == SubscriptionLifecycle.ACTIVE