.NET Workflows - Add unit tests for ForeachExecutor (Declarative Workflows)

[Copilot]

Motivation and Context

The ForeachExecutor class had no unit test coverage. Unit tests ensure correctness of loop initialization, value iteration logic, index tracking, and state reset behavior.

Description

• Created ForeachExecutorTest.cs with 100% line/branch coverage
• Updated WorkflowActionExecutorTest to support non-discrete actions
• Fine-tuned some method names
• Updated semantics for DeclarativeWorkflowTest

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 unit test coverage for the declarative workflows ForeachExecutor, and updates the workflow visitor wiring to use a new loop-completion method name (CompleteAsync) instead of ResetAsync.

Changes:

• Added ForeachExecutorTest.cs with unit tests covering initialization, iteration, index handling, completion, and reset behavior.
• Refactored ForeachExecutor end-of-loop behavior by renaming ResetAsync → CompleteAsync and extracting shared state-reset logic.
• Enhanced WorkflowActionExecutorTest helpers to support executing chained executors and selectively asserting discrete action events.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.UnitTests/ObjectModel/WorkflowActionExecutorTest.cs	Adds helper overloads to execute single/multiple executors and optionally assert discrete action events.
dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.UnitTests/ObjectModel/ForeachExecutorTest.cs	New unit tests for ForeachExecutor execution paths and loop behaviors.
dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.UnitTests/CodeGen/ForeachTemplateTest.cs	Updates codegen test expectation from ResetAsync to CompleteAsync.
dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/ForeachExecutor.cs	Renames loop completion method and factors out shared reset logic; adjusts initialization behavior.
dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/Interpreter/WorkflowTemplateVisitor.cs	Updates generated workflow template naming to reference CompleteAsync.
dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/Interpreter/WorkflowActionVisitor.cs	Updates workflow graph wiring to invoke CompleteAsync at loop end.