Do not include Maui.InTree.targets for an AspNet.Core project

[simonrozsival]

Description of Change

After we introduced the Binding Source Generator, it started generating code also in the Essentials.Sample.Server.WebAuthenticator.csproj which is an ASP.NET Core server and shouldn't include the analzyer:

D:\a\_work\1\s\artifacts\obj\Essentials.Sample.Server.WebAuthenticator\Release\net9.0\Microsoft.Maui.Controls.BindingSourceGen\Microsoft.Maui.Controls.BindingSourceGen.BindingSourceGenerator\GeneratedBindingInterceptorsCommon.g.cs(40,39): error CS0246: The type or namespace name 'BindingMode' could not be found (are you missing a using directive or an assembly reference?) [D:\a\_work\1\s\src\Essentials\samples\Sample.Server.WebAuthenticator\Essentials.Sample.Server.WebAuthenticator.csproj]
D:\a\_work\1\s\artifacts\obj\Essentials.Sample.Server.WebAuthenticator\Release\net9.0\Microsoft.Maui.Controls.BindingSourceGen\Microsoft.Maui.Controls.BindingSourceGen.BindingSourceGenerator\GeneratedBindingInterceptorsCommon.g.cs(40,57): error CS0246: The type or namespace name 'BindableProperty' could not be found (are you missing a using directive or an assembly reference?) [D:\a\_work\1\s\src\Essentials\samples\Sample.Server.WebAuthenticator\Essentials.Sample.Server.WebAuthenticator.csproj]
D:\a\_work\1\s\artifacts\obj\Essentials.Sample.Server.WebAuthenticator\Release\net9.0\Microsoft.Maui.Controls.BindingSourceGen\Microsoft.Maui.Controls.BindingSourceGen.BindingSourceGenerator\GeneratedBindingInterceptorsCommon.g.cs(47,39): error CS0246: The type or namespace name 'BindingMode' could not be found (are you missing a using directive or an assembly reference?) [D:\a\_work\1\s\src\Essentials\samples\Sample.Server.WebAuthenticator\Essentials.Sample.Server.WebAuthenticator.csproj]

It seems that the problem is that we're including Maui.InTree.targets for non-MAUI projects in src/Essentials/samples/Directory.Build.targets (see history of that file). I don't understand why we needed to import that targets file, it doesn't seem to be necessary to build the ASP.NET Core project.

/cc @jonathanpeppers @PureWeen @mattleibow @StephaneDelcroix

[mattleibow]

It is needed for the essentials maui app sample in there. However, maybe we can just put the targets file in the app folder instead?

[simonrozsival]

@mattleibow I see. The $(UseMaui)' != 'true' condition confused me. Now that I looked closely I noticed that the sample MAUI app doesn't set UseMaui=true. I will move the file.

EDIT: so the UseMaui property is set in the Directory.Build.props based on the value of the UseWorkload property. Now I'm less confident in making this change and I will need to revisit this tomorrow.

[jonathanpeppers]

Yes, it doesn't seem like this project would use UseMaui=true, so you shouldn't need Maui.InTree.targets.