AOT publish doesn't work if PackAsTool is set (a regression)

[jjonescz]

1. dotnet new console
2. Set properties PublishAot=true and PackAsTool=true
3. Run dotnet publish with .NET 9.0.304 -> the app is published with NativeAOT as expected
4. Run dotnet publish with .NET 10.0.100-preview.7.25380.108 -> the app is published WITHOUT NativeAOT, no error is reported

[baronfel]

This is happening because the PackTool.targets are imported for all projects where PackAsTool is true, and those targets do some overwriting of project properties. In general we should aim to only do these modifications if we are actually going to be packaging the project as a tool. Some options:

• Condition the Import of the PackTool.targets on _IsPacking=true
  • I hate this, as is continues the problematic pattern of the entrypoint changing the characteristics of the loaded projects
• Push the property-overridding and computation down into a separate Target that is then configured to be invoked very early in the actual packing process

We definitely need to get this fixed for RC2.