Add selectedOptions attribute to product_variants schema and stream

[leobossmann]

The selectedOptions attribute contains information on product variants (e.g. size, color, material). Those attributes were present in the older version of the tap as option1, option2, option3 and were missing from the new version

Description of change

• Add fields to schema (name/value for selectedOptions)
• Add stream config (array containing selectedOptions objects)

QA steps

• manual qa steps passing (list below)
  • with Fix fulfillment order JSON schema #240 and Fix typo in assertion method #241 applied manually executing the CircleCI tasks pass except integration tests

Risks

Moderate, no code changes, just modifications to GraphQL schema and stream config

Rollback steps

• revert this branch

AI generated code

GitHub Copilot was used for research, bug fixing and code completion. All code was reviewed manually before committing

[leobossmann]

I believe the CircleCI run to fail

I tried to run most of the tasks in .circleci/config.yml manually:

• pylint tap_shopify -d missing-docstring,too-many-branches,consider-using-f-string,consider-using-generator,consider-using-dict-items,unnecessary-dunder-call,duplicate-code,too-many-lines passes without issue
• JSON Schema validation (custom script) found an error in tap_shopify/schemas/fulfillment_orders.json. Fixed in Fix fulfillment order JSON schema #240
• coverage run -m pytest tests/unittests failed in tests/unittests/tast_date_window.py. Fixed in Fix typo in assertion method #241

Once these are merged (and integration tests pass) CircleCI build should be successful