Test suite refactor

[Sachin1043]

Refactor: modernize the ecommerce_integrations test suite

Summary

Migrates every integration's tests (Amazon, Shopify, Unicommerce) onto a single shared test-suite base, modernizes the app's source for ERPNext v16, and bumps dependencies. Net effect is a leaner, self-contained, and faster test suite with the app code updated to current framework APIs.

Test infrastructure

• New shared base: ecommerce_integrations/tests/utils.py (EcommerceTestSuite) — a central suite all integration tests now inherit from, providing consistent setup, fixture loading (load_fixture), and transaction-based isolation.
• Retired the old bootstrap: removed the before_tests hook (hooks.py) and deleted ecommerce_integrations/utils/before_test.py.
• Per-integration test utils modernized: new amazon/tests/utils.py; rewritten shopify/tests/utils.py and unicommerce/tests/utils.py — HTTP now mocked with the responses library instead of live/ad-hoc mocks.
• Fixtures reorganized: Amazon test_data.json moved into amazon/tests/fixtures/; removed the obsolete shopify/tests/test_order.py.
• Rewrote the bulk of the Amazon / Shopify / Unicommerce test modules to use the shared helpers.

Source modernization (ERPNext v16 compatibility)

• Updated ERPNext imports from the doctype controllers to the new mapper modules — make_sales_invoice, make_delivery_note, make_sales_return — across shopify/fulfillment.py, shopify/invoice.py, unicommerce/invoice.py, unicommerce/delivery_note.py, unicommerce/cancellation_and_returns.py.
• unicommerce/invoice.py: replaced a raw frappe.db.sql UPDATE with the frappe.qb query builder.
• ecommerce_integration_log.py: made logging test-safe — skips commit()/rollback() under frappe.flags.in_test so log writes don't break test isolation.

Efficiency cleanups

• unicommerce/tests/utils.py: simplified the enable_setting decorator — dropped the redundant read + finally restore (per-test rollback already undoes it).
• amazon/tests/utils.py: removed the pointless retry/time.sleep(3) loop in the mock SP-API caller (mocks are deterministic).
• shopify/.../test_shopify_import_products.py: reuse the inherited load_fixture() instead of manual file I/O.
• unicommerce/tests/test_customer.py: removed a redundant setUpClass override (base suite already seeds channels via the non-deprecated path).

Dependencies (pyproject.toml)

• boto3 ~=1.28.10 -> >=1.35.0
• Added dev-dependency responses == 0.23.1 (HTTP mocking).