Process termination

[tmat]

Simplify process termination. Unify two code paths that were used to gracefully terminate process to a single one.
Converts ProcessRunner to an object that stores cancellation token that is triggered by Ctrl+C. Then use it in ProcessRunner methods to detect whether the process termination was initiated via Ctrl+C or otherwise.

[tmat]

@DustinCampbell @phil-allen-msft ptal

[Copilot]

Pull Request Overview

This PR simplifies process termination by unifying code paths and centralizing the handling of process cancellation via a dedicated ProcessRunner instance. Key changes include:

• Replacing static process termination calls with an instance-based ProcessRunner that accepts a cancellation token.
• Updating various methods across tests and production code to incorporate caller information for logging and to align with the new ProcessRunner pattern.
• Adjusting reporter messages and test expectations to match the unified termination behavior.

Reviewed Changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
test/dotnet-watch.Tests/Watch/Utilities/WatchableApp.cs	Updated types and assertions to use DebugTestOutputLogger and new caller info.
test/dotnet-watch.Tests/Utilities/MockFileSetFactory.cs	Revised instantiation including a redundant ternary expression for environment options and addition of ProcessRunner argument.
test/dotnet-watch.Tests/MsBuildFileSetFactoryTest.cs, NoRestoreTests.cs, MSBuildEvaluationFilterTest.cs, ...	Updated tests to consistently instantiate and pass ProcessRunner.
src/BuiltInTools/dotnet-watch/Program.cs, DotNetWatcher.cs, DotNetWatchContext.cs, ...	Revised process creation and termination calls to use ProcessRunner and updated reporter messaging.
src/BuiltInTools/dotnet-watch/Internal/ProcessRunner.cs	Refactored process termination logic to be instance-based and added asynchronous helper methods.
src/BuiltInTools/dotnet-watch/HotReload*	Updated hot-reload related components to work with the new process termination logic.

[marcpopMSFT]

only failure was from the known container issue that dnceng is working on. Requested to merge on red