Client Republish improvements

[mregen]

Proposed changes

• only republish available sequence numbers
• store republish result to handle unsuccessful message republish in main loop
• republish in parallel instead of sequential to reduce processing time

Related Issues

• Fixes #

Types of changes

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• Bugfix (non-breaking change which fixes an issue)
• Enhancement (non-breaking change which adds functionality)
• Test enhancement (non-breaking change to increase test coverage)
• Breaking change (fix or feature that would cause existing functionality to not work as expected, requires version increase of Nuget packages)
• Documentation Update (if none of the other choices apply)

Checklist

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• I have read the CONTRIBUTING doc.
• I have signed the CLA.
• I ran tests locally with my changes, all passed.
• I fixed all failing tests in the CI pipelines.
• I fixed all introduced issues with CodeQL and LGTM.
• I have added tests that prove my fix is effective or that my feature works and increased code coverage.
• I have added necessary documentation (if appropriate).
• Any dependent changes have been merged and published in downstream modules.

Further comments

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[codecov]

Codecov Report

Attention: Patch coverage is 93.54839% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 53.97%. Comparing base (a64c5a9) to head (84316fe).

Files	Patch %	Lines
Libraries/Opc.Ua.Client/Subscription.cs	96.42%	0 Missing and 1 partial ⚠️
...Opc.Ua.Core/Security/Constants/SecurityPolicies.cs	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2468      +/-   ##
==========================================
+ Coverage   53.87%   53.97%   +0.10%     
==========================================
  Files         334      334              
  Lines       64455    64472      +17     
  Branches    13251    13253       +2     
==========================================
+ Hits        34726    34801      +75     
+ Misses      25968    25919      -49     
+ Partials     3761     3752       -9     

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