Avoid packing absolute paths and development dependencies

[kzu]

Summary

• Absolute source paths, typical of assemblies from the NuGet global packages folder, are no longer written into package entries. NuGet rejects those paths as NU1402.
• Development dependencies and their own dependencies are excluded from transitive packing.

Test plan

• AssignPackagePath covers an ignore-folder file outside the project, an absolute lib TargetPath, and a relative TargetPath with a rooted RelativeDir
• InferImplicitPackageReference covers a development-dependency root, a transitive development dependency, and inference when no package definitions are supplied

[kzu]

🧪 Details on Ubuntu 24.04.5 LTS

🧪 Details on Microsoft Windows 10.0.26100

from dotnet-retest v1.0.0 on .NET 10.0.12 with 💜 by @devlooped