Restore capability to infer project configurations from usage

Until we switch to the new Configurations/Platforms approach in the SDK,
we still need to provide the default property groups so that the project
system can infer them for Restore.

Author: kzu

src/VisualStudio/NuGet.Packaging.VisualStudio.15/ProjectSystem/NuProjCapabilities.cs

@@ -5,11 +5,11 @@ namespace NuGet.Packaging.VisualStudio
     internal static class NuProjCapabilities
     {
 		public const string NuProj = "PackagingProject";
-
-		public const string HandlesOwnReload = ProjectCapabilities.HandlesOwnReload;
 		public const string OpenProjectFile = nameof(OpenProjectFile);
 
-		public const string DefaultCapabilities = HandlesOwnReload + "; " +
-												  OpenProjectFile;
+		public const string DefaultCapabilities = 
+			ProjectCapabilities.HandlesOwnReload + "; " +
+			OpenProjectFile + ";" +
+			ProjectCapabilities.ProjectConfigurationsInferredFromUsage;
     }
 }

src/VisualStudio/NuGet.Packaging.VisualStudio.15/Templates/Projects/Nuget/Package/Package.nuproj

@@ -21,9 +21,6 @@
 		<TargetFramework>netstandard1.0</TargetFramework>
 		<PackageTargetFallback>net11;net20;net35;net40;net403;net45;net451;net452;net46;net461;net462;net47;netcore;netcore45;netcore451;netcore50;win8;win81;win10;sl4;sl5;wp;wp7;wp75;wp8;wp81;wpa81;uap;uap10;netstandard1.0;netstandard1.1;netstandard1.2;netstandard1.3;netstandard1.4;netstandard1.5;netstandard1.6;netstandard2.0;netcoreapp1.0;netcoreapp2.0;monoandroid;monotouch;monomac;xamarinios;xamarinmac;xamarinpsthree;xamarinpsfour;xamarinpsvita;xamarinwatchos;xamarintvos;xamarinxboxthreesixty;xamarinxboxone</PackageTargetFallback>
 
-		<Configurations>Debug;Release</Configurations>
-		<Platforms>AnyCPU</Platforms>
-		
 		<Configuration Condition="'$(Configuration)' == ''">Debug</Configuration>
 		<OutputPath>bin\$(Configuration)\</OutputPath>
 	</PropertyGroup>

src/VisualStudio/NuGet.Packaging.VisualStudio.15/project.json

@@ -17,7 +17,7 @@
     "MSBuilder.Introspect": "0.1.5",
     "MSBuilder.ThisAssembly.Project": "0.3.3",
     "MSBuilder.VsixDependency": "0.2.11",
-    "MSBuilder.VsixInstaller": "0.2.13",
+    "MSBuilder.VsixInstaller": "0.2.15",
     "VSLangProj150": "1.0.0",
     "VSSDK.ComponentModelHost.11": "11.0.4"
   },

src/VisualStudio/NuGet.Packaging.VisualStudio/Targets/NuGet.Packaging.Authoring.targets

@@ -70,6 +70,9 @@ Copyright (c) .NET Foundation. All rights reserved.
   <ItemGroup>
     <ProjectCapability Include="PackagingProject" />
 
+    <!-- Allows configurations inferred from Condition="CONFIG|PLATFORM" usage -->
+    <ProjectCapability Include="ProjectConfigurationsInferredFromUsage" />
+
     <!-- DependenciesTree capability lights up a Dependencies tree node and it's sub node providers-->
     <ProjectCapability Include="DependenciesTree" />