Don't explicitly import Arcade SDK in AfterSigning.targets

[wtgodbe]

Attempts to resolve #22244

Internal build: https://dev.azure.com/dnceng/internal/_build/results?buildId=667109&view=results

[wtgodbe]

New build: https://dev.azure.com/dnceng/internal/_build/results?buildId=667255&view=results

[wtgodbe]

The internal build produced the checksum files without the warnings.

The issue was that sdk.props and AfterSigning.proj (both in Arcade) import some of the same files

[dougbu]

Might work but it's not clear why AfterSigning.targets uses the Arcade SDK at all. Isn't it imported from an Arcade SDK project. We don't do anything similar in Publishing.props or Signing.props for example.

[dougbu]

Why is this <Import/> both still needed and 🆗❔

[wtgodbe]

The checksums weren't produced without it, because SDK.targets imports https://github.com/dotnet/arcade/blob/master/src/Microsoft.DotNet.Arcade.Sdk/tools/Imports.targets, which imports GenerateChecksums.targets. AfterSigning.targets doesn't import that. Presumably publishing/signing.props don't need to import anything because they don't use custom tasks like GenerateChecksums

[wtgodbe]

Is there a way to directly import a specific .targets file from the Arcade SDK (@riarenas @JohnTortugo @chcosta)? If so that'd probably be best

[wtgodbe]

ping @riarenas @JohnTortugo @chcosta + @mmitche

[wtgodbe]

Also @jcagme

[riarenas]

I'm not sure if there's a way to import a specific targets file from an msbuild sdk

[wtgodbe]

@rainersigwald confirmed we can't import a specific .targets file without calculating the path to the file on-disk, so I'll just merge this as-is