Improve native build and mark our official build as CFS Clean

[ericstj]

The CFS Clean marking will prevent our build from accessing public packaging endpoints (like NuGet.org, myget.org, etc).
See https://eng.ms/docs/cloud-ai-platform/devdiv/one-engineering-system-1es/1es-build/cloudbuild/resolving-cfs-s360-items

The other settings are just various native toolchain improvements like deterministic build, source linking, etc. I also enabled the repo to build with Dev18 while I was at it.

[Copilot]

Pull Request Overview

This PR improves the native build system by implementing CFS Clean marking to prevent access to public packaging endpoints and adds various native toolchain improvements. The changes also enable Dev18 (Visual Studio 2026) support for the build system.

• Adds CFS Clean network isolation policy in the CI build pipeline
• Implements native build improvements including deterministic builds, source linking, and link-time code generation
• Adds support for Visual Studio 2026 (Dev18) in the native build system

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
build/vsts-ci.yml	Adds CFS Clean network isolation policy setting
src/Native/build.cmd	Adds VS2026 support and fixes script directory path handling
src/Native/Native.proj	Adds native source link file generation
src/Native/CMakeLists.txt	Implements deterministic build flags, source linking, and removes RelWithDebInfo configuration
src/Native/gen-buildsys-win.bat	Adds debug echo statement for CMake command

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.02%. Comparing base (b28b6d4) to head (35e023a).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7516   +/-   ##
=======================================
  Coverage   69.02%   69.02%           
=======================================
  Files        1482     1482           
  Lines      274092   274092           
  Branches    28266    28266           
=======================================
+ Hits       189193   189202    +9     
+ Misses      77511    77505    -6     
+ Partials     7388     7385    -3     

Flag	Coverage Δ
Debug	69.02% <ø> (+<0.01%)	⬆️
production	63.31% <ø> (+<0.01%)	⬆️
test	89.47% <ø> (ø)

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[ericstj]

Official build. https://dev.azure.com/dnceng/internal/_build/results?buildId=2807323&view=results

[ericstj]

We should wait for this to merge #7519 then queue another official build with that change before merging this.

[tarekgh]

I had the impression is we need updated CMake to make this work. Looks this was not true then. Thanks for fixing that.

[ericstj]

I had the impression is we need updated CMake to make this work. Looks this was not true then. Thanks for fixing that.

You do need a locally installed CMake that can understand Dev18. I think 4.1.1 added support. I used cmake version 4.1.2.