fix: scope Cancel request matching to the current session (#4023)

[romanett]

Backport of 70c74e7 from master to master378.

Summary

Scopes Cancel request matching to the caller's session and adds a regression test verifying a request handle can no longer cancel work belonging to another session.

Problem

Per OPC UA Part 4, Cancel applies to a request handle from the same session that issued the original request. Previously StandardServer.CancelAsync validated the caller's session but forwarded only the raw requestHandle to RequestManager.CancelRequests, which iterated the global outstanding-request table and canceled every request whose ClientHandle matched — regardless of owning session. Since request handles are only session-scoped and different sessions can reuse the same value, one session could cancel another session's in-flight request.

Changes

• Pass the validated caller session id from StandardServer.CancelAsync into RequestManager.CancelRequests.
• Restrict RequestManager.CancelRequests to requests whose SessionId and ClientHandle both match.
• Update the existing request-manager test call and add CancelRequestsDoesNotCancelMatchingHandleFromDifferentSession regression test.

Notes on the backport

The master378 branch predates the RequestLifetime cancellation model and the SessionPublishQueueTests present on master, so those parts of the original commit do not apply. The core fix and the regression test were adapted to this branch's SetStatusCode/OperationStatus model. Opc.Ua.Server.Tests builds clean and both RequestManagerTests pass.

Co-authored-by: Copilot App 223556219+Copilot@users.noreply.github.com

[codecov]

Codecov Report

❌ Patch coverage is 33.33333% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 60.23%. Comparing base (db256c6) to head (d079262).

Files with missing lines	Patch %	Lines
Libraries/Opc.Ua.Server/Server/StandardServer.cs	0.00%	4 Missing ⚠️

❌ Your patch check has failed because the patch coverage (33.33%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@              Coverage Diff              @@
##           master378    #4267      +/-   ##
=============================================
+ Coverage      60.19%   60.23%   +0.03%     
=============================================
  Files            378      378              
  Lines          79067    79071       +4     
  Branches       13838    13838              
=============================================
+ Hits           47598    47625      +27     
+ Misses         27047    27023      -24     
- Partials        4422     4423       +1     

Files with missing lines	Coverage Δ
Libraries/Opc.Ua.Server/Server/RequestManager.cs	62.35% <100.00%> (+0.44%)	⬆️
Libraries/Opc.Ua.Server/Server/StandardServer.cs	70.86% <0.00%> (-0.13%)	⬇️

... and 11 files with indirect coverage changes

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