Picked this up from #324
I need some feedback whether this is the right direction or not.

Description

This PR modernizes the Azure release pipeline to match the current versioning and packaging strategy in the repository.

What changed

• Replaced the previous branch/tag-driven Azure pipeline with a manual release pipeline.
• Added release parameters:
  • Version Suffix (for preview releases)
  • Allow Breaking Changes (to optionally bypass package validation/API compatibility checks)
  • Publish Packages To NuGet (safe default is off)
• Installed required SDKs in pipeline:
  • .NET 6
  • .NET 8
  • .NET 10
• Updated build and pack steps to:
  • use the version from Directory.Build.props
  • support optional version suffix
  • set ContinuousIntegrationBuild=true for official release builds
• Added guarded NuGet publishing:
  • only runs when publishing is enabled
  • validates NuGetApiKey before push
• Kept artifact publication for:
  • generated NuGet packages
  • CompatibilitySuppressions file (when present)
• Updated Directory.Build.props so ContinuousIntegrationBuild is enabled in Azure Pipelines as well (TF_BUILD), not only in GitHub Actions.

Draft next steps

• Run both the azure release pipeline as well as the github actions and report their behaviour.

Fixes: #323