Introduce a common pagination utility for raw API calls

[pritishpai]

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Problem statement

Several places in UCX perform manual pagination over raw API responses, each implementing their own loop:
workspace_access/groups.py — SCIM startIndex/count offset pagination for account groups ([introduced in #PR_NUMBER])
workspace_access/generic.py — page_token/next_page_token cursor pagination for feature store listing
assessment/dashboards.py — iterator-based pagination for Redash queries
Each re-implements the same boilerplate (loop, accumulate, terminate). This makes it easy to introduce bugs (e.g., missing pagination was the root cause of not fetching all Account Groups at a customer) and increases maintenance burden.

Proposed Solution

Create a shared pagination utility and refactor all separate pagination attempts to use the utility.

Additional Context

No response