fix: add logic to check for if gitlab instance is ee or ce so graphql query doesn't fail for ce instances
Summary
This change adds support for distinguishing between GitLab Community Edition (CE) and Enterprise Edition (EE) instances when fetching work items. Previously, the API always requested certain EE-only fields (color, health status, iteration, status, weight) regardless of the instance type, which could cause errors on non-Enterprise instances.
Now, before building any work item query, the code first checks whether the connected GitLab instance is Enterprise Edition. EE-only fields are only included in the query when the instance actually supports them. This check is performed once and cached, so subsequent calls don't repeat the lookup.
The tests were updated to simulate this metadata check and to use a more flexible assertion approach — instead of comparing the full query against a fixed file, they now verify that key expected pieces are present in the query, since the exact query content varies depending on the instance type.