Added new GitHub action for manual integration test run based on PR

[dmytrostruk]

Motivation and Context

• Added a new "Integration Tests (Manual)" workflow to run integration tests against any open PR by entering its number in the Actions UI
• Made existing dotnet-build-and-test and python-merge-tests workflows callable via workflow_call with an optional checkout-ref input
• The new workflow resolves the PR's head SHA and delegates to the existing workflows, which handle path detection, environment setup, and test execution

It would be also possible to run this workflow with:

# By PR number                                                                                                  
gh workflow run "Integration Tests (Manual)" --field pr-number=4135
                                                                                                                  
# By branch name                                                                            
gh workflow run "Integration Tests (Manual)" --field branch=my-feature-branch

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines
• All unit tests pass, and I have added new tests where possible
• Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.

[Copilot]

Pull request overview

Adds a manually-triggered GitHub Actions workflow to run integration tests against an open PR by PR number, by resolving the PR’s head revision and reusing existing .NET and Python CI workflows.

Changes:

• Added Integration Tests (Manual) workflow that resolves PR info and calls existing .NET/Python test workflows.
• Made dotnet-build-and-test and python-merge-tests reusable via workflow_call with an optional checkout-ref input.
• Updated checkout steps in the called workflows to use the provided checkout-ref.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
.github/workflows/integration-tests-manual.yml	New manual workflow to resolve PR and invoke existing .NET/Python test workflows.
.github/workflows/dotnet-build-and-test.yml	Adds workflow_call + checkout-ref input and checks out that ref.
.github/workflows/python-merge-tests.yml	Adds workflow_call + checkout-ref input and checks out that ref.

[TaoChenOSU]

Will this allow external folks to run our integration tests?

[dmytrostruk]

Will this allow external folks to run our integration tests?

It shouldn't, workflow_dispatch can only be triggered by users with write access to the repository.