refactore tests and some helper methods

gso/cli/imports.py

gso/products/__init__.py

gso/services/subscriptions.py

gso/utils/helpers.py

gso/workflows/l3_core_service/migrate_l3_core_service.py

test/conftest.py

test/fixtures/edge_port_fixtures.py

test/fixtures/iptrunk_fixtures.py

test/fixtures/l3_core_service_fixtures.py

test/fixtures/lan_switch_interconnect_fixtures.py

test/fixtures/office_router_fixtures.py

test/fixtures/opengear_fixtures.py

test/fixtures/router_fixtures.py

test/fixtures/site_fixtures.py

test/fixtures/super_pop_switch_fixtures.py

test/fixtures/switch_fixtures.py

test/services/test_infoblox.py

test/services/test_netbox_client.py

test/workflows/__init__.py

test/workflows/edge_port/test_create_edge_port.py