If NuGet baseline package validation fails, generate a new artifact with the new CompatibilitySuppressions.xml file (OSOE-1103)

[sarahelsaig]

The NuGet workflows have all the information ready to prepare this file for us, so it would be nice.

• Generate a CompatibilitySuppressions.xml file, both in validate-nuget-publish and publish-nuget, if NuGet baseline package validation fails, and make it downloadable as an artifact. This needs /p:GenerateCompatibilitySuppressionFile=true in the dotnet pack calls.
• Update the docs under https://github.com/Lombiq/Open-Source-Orchard-Core-Extensions?tab=readme-ov-file#opening-pull-requests.
• If Indicate if a PR has breaking changes, as discovered by validate-nuget-publish (OSOE-1101) #466 was done earlier, then change the comment added by it to refer to using this artifact instead of instructing how to generate the file.

Jira issue

[Piedone]

Yep!