Add codeflow documentation in PR description

[adamzip]

#4463 (comment)

Pull Request Overview

This pull request adds an extra parameter (isForwardFlow) to several methods in the pull request builder and updater classes to enable differential behavior in codeflow updates, along with corresponding updates to tests and method calls.

• Updated method signatures in PullRequestBuilder to include the new isForwardFlow parameter.
• Adjusted test cases in PullRequestBuilderTests to supply the new parameter and updated expected description formatting.
• Modified PullRequestUpdater methods to pass through the isForwardFlow parameter to maintain consistent behavior.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/ProductConstructionService/ProductConstructionService.DependencyFlow/PullRequestBuilder.cs	Added isForwardFlow parameter in method signatures and updated PR description formatting with a new markdown note.
test/ProductConstructionService.DependencyFlow.Tests/PullRequestBuilderTests.cs	Updated test calls and expected outputs to include isForwardFlow parameter for codeflow descriptions.
src/ProductConstructionService/ProductConstructionService.DependencyFlow/PullRequestUpdater.cs	Updated method calls to pass the isForwardFlow parameter in PR update/creation functions.

Comments suppressed due to low confidence (1)

src/ProductConstructionService/ProductConstructionService.DependencyFlow/PullRequestBuilder.cs:257

• The inserted markdown note block in the PR description contains extra leading whitespace that may affect the rendered formatting. Consider normalizing the indentation to ensure consistent display.

                > [!NOTE]