Return most recent result diff from useFragment, update test

[alessbell]

This includes the same fix and adapts the tests from #9918 while targeting the release-3.7 branch. The tests use useQuery and the new test fails if the diff in src/react/hooks/useFragment.ts is reverted.

Checklist:

• If this PR is a new feature, please reference an issue where a consensus about the design was reached (not necessary for small changes)
• Make sure all of the significant new logic is covered by tests

[alessbell]

@benjamn the diff here is identical to #9918 with the exception of src/react/hooks/__tests__/useFragment.test.tsx L836 (calling useQuery instead of useBackgroundQuery)