Remove NuGet.Packaging.Core references from arcade tasks.

[nkolev92]

• This issue is blocking
• This issue is causing unreasonable pain

In NuGet 5.0 (shipped in 2019), we removed NuGet.Packaging.Core and merged it into NuGet.Packaging.

We ended up creating typeforwarders in NuGet.Packaging.Core , and now we'd likely stop building it.

The biggest reason why we're still building is https://github.com/dotnet/sdk/blob/23bbdf8e62544b04afd333920b109877f427b637/src/Cli/Microsoft.DotNet.Cli.Utils/Microsoft.DotNet.Cli.Utils.csproj#L49.

To allow us to stop building it, we'd need to upgrade all arcade tasks to target versions higher than 5.0.

Release Note Category

• Feature changes/additions
• Bug fixes
• Internal Infrastructure Improvements

Release Note Description

N/A