Pin MSBuild references to a lower version

Always referencing the latest MSBuild means that some things like the
SDK resolver would be forced to target MSBuild's latest runtime, and
that would break compat with uses. For instance, VSMac is currently on
.NET 6.0 and can't run a net7.0 resolver.

We do, however, want to always _ship_ the latest MSBuild.

Author: rainersigwald

eng/Versions.props

@@ -107,11 +107,12 @@
   <PropertyGroup>
     <!-- Dependencies from https://github.com/Microsoft/msbuild -->
     <MicrosoftBuildPackageVersion>17.4.0-preview-22469-04</MicrosoftBuildPackageVersion>
-    <!-- .NET Framework-targeted tasks will need to run in an MSBuild that is older than the very latest,
+    <MicrosoftBuildCurrentPackageVersion>$(MicrosoftBuildPackageVersion)</MicrosoftBuildCurrentPackageVersion>
+    <!-- Some tasks and the resolver will need to run in an MSBuild that is older than the very latest,
           so target one that matches the version in minimumMSBuildVersion.
 
           This avoids the need to juggle references to packages that have been updated in newer MSBuild. -->
-    <MicrosoftBuildPackageVersion Condition=" '$([MSBuild]::GetTargetFrameworkIdentifier($(TargetFramework)))' == '.NETFramework' and exists('$(RepoRoot)\src\Layout\redist\minimumMSBuildVersion')">$([System.IO.File]::ReadAllText('$(RepoRoot)\src\Layout\redist\minimumMSBuildVersion').Trim())</MicrosoftBuildPackageVersion>
+    <MicrosoftBuildPackageVersion Condition="exists('$(RepoRoot)\src\Layout\redist\minimumMSBuildVersion')">$([System.IO.File]::ReadAllText('$(RepoRoot)\src\Layout\redist\minimumMSBuildVersion').Trim())</MicrosoftBuildPackageVersion>
     <MicrosoftBuildFrameworkPackageVersion>$(MicrosoftBuildPackageVersion)</MicrosoftBuildFrameworkPackageVersion>
     <MicrosoftBuildRuntimePackageVersion>$(MicrosoftBuildPackageVersion)</MicrosoftBuildRuntimePackageVersion>
     <MicrosoftBuildLocalizationPackageVersion>17.4.0-preview-22469-04</MicrosoftBuildLocalizationPackageVersion>

src/Cli/Microsoft.DotNet.Cli.Utils/Microsoft.DotNet.Cli.Utils.csproj

@@ -22,7 +22,7 @@
 
   <Target Name="VerifyMSBuildDependency" BeforeTargets="ResolveAssemblyReferences" Condition="'$([MSBuild]::GetTargetFrameworkIdentifier($(TargetFramework)))' == '.NETCoreApp'">
     <PropertyGroup>
-      <MSBuildPathInPackage>$(PkgMicrosoft_Build_Runtime)\contentFiles\any\net7.0\MSBuild.dll</MSBuildPathInPackage>
+      <MSBuildPathInPackage>$(PkgMicrosoft_Build_Runtime)\contentFiles\any\net6.0\MSBuild.dll</MSBuildPathInPackage>
     </PropertyGroup>
     <Error Condition="!Exists('$(MSBuildPathInPackage)')" Text="Something moved around in Microsoft.Build.Runtime, adjust code here accordingly." />
     <ItemGroup>

src/Layout/tool_msbuild/tool_msbuild.csproj

@@ -7,7 +7,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.Build.Runtime" Version="$(MicrosoftBuildRuntimePackageVersion)" />
+    <PackageReference Include="Microsoft.Build.Runtime" Version="$(MicrosoftBuildRuntimeCurrentPackageVersion)" />
     <PackageReference Include="Microsoft.Build.Localization" Version="$(MicrosoftBuildLocalizationPackageVersion)" />
     <PackageReference Include="System.Resources.Extensions" Version="$(SystemResourcesExtensionsPackageVersion)" />
   </ItemGroup>