Extend NuGet package validation

[martincostello]

Use Meziantou.Framework.NuGetPackageValidation.Tool to extend NuGet package validation.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.15%. Comparing base (954ad8d) to head (271578d).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2762   +/-   ##
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  Coverage   96.15%   96.15%           
=======================================
  Files         309      309           
  Lines        7123     7123           
  Branches     1005     1005           
=======================================
  Hits         6849     6849           
  Misses        221      221           
  Partials       53       53           

Flag	Coverage Δ
linux	96.15% <ø> (ø)
macos	96.15% <ø> (ø)
windows	96.14% <ø> (ø)

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[Copilot]

Pull Request Overview

This PR adds the Meziantou.Framework.NuGetPackageValidation.Tool to extend NuGet package validation capabilities beyond the existing dotnet-validate tool.

• Adds Meziantou NuGet package validation tool alongside existing validation
• Integrates GitHub token support for enhanced validation features
• Updates workflow to install and use both validation tools

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
.github/workflows/build.yml	Updates workflow to install and use the new Meziantou validation tool with GitHub token support
.config/dotnet-tools.json	Adds the Meziantou NuGet package validation tool and sets rollForward to false for dotnet-validate

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