merge sessionChanges before finalizing session after refresh

[wolfgangGoedel]

• All new/changed/fixed functionality is covered by tests (or N/A)
• I have added documentation for all new/changed functionality (or N/A)

📋 Changes

The beforeSessionSaved hook should be called with the updated session after the tokenSet has been refreshed. A recent change in this PR fixed the behavior when requesting the access token via the token route. Thanks again for having responded to my issue so promptly.

One case remains though where the old, buggy behavior remains: when getAccessToken is been called server side like it would be in next middleware. This PR fixes the issue in the same way the issue has been fixed elsewhere.

📎 References

related PR: fix: make sure beforeSessionSaved hook gets the updated token after refresh
initial issue: beforeSessionSaved behaves differently when called after login or after token refresh

🎯 Testing

Unit tests included with the PR

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.88%. Comparing base (4a5834f) to head (0506e1e).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2401      +/-   ##
==========================================
- Coverage   87.90%   87.88%   -0.03%     
==========================================
  Files          37       37              
  Lines        4127     4120       -7     
  Branches      818      819       +1     
==========================================
- Hits         3628     3621       -7     
  Misses        496      496              
  Partials        3        3              

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