feat(agent): Support updating existing unit tests

[skarllot]

Pull Request

Details on the issue fix or feature implementation

• Support updating existing unit tests after code changes

Confirm the following

• I started this PR by branching from the head of the default branch
• I have targeted the PR to merge into the default branch
• I have included unit tests for the issue/feature
• I have successfully run a local build

[codecov]

Codecov Report

Attention: Patch coverage is 97.14286% with 4 lines in your changes missing coverage. Please review.

Project coverage is 54.98%. Comparing base (e5672b7) to head (c712aec).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...ons/UpdateUnitTest/UpdateUnitTestChatDefinition.cs	96.15%	1 Missing and 1 partial ⚠️
...Operations/UpdateUnitTest/UpdateUnitTestCommand.cs	98.50%	0 Missing and 1 partial ⚠️
src/FlowPair/Program.cs	94.73%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #31      +/-   ##
==========================================
+ Coverage   54.62%   54.98%   +0.35%     
==========================================
  Files          68       71       +3     
  Lines        1384     1515     +131     
  Branches      106      110       +4     
==========================================
+ Hits          756      833      +77     
- Misses        614      666      +52     
- Partials       14       16       +2     

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