Ensure DCP path is valid (#14415)

Author: sebastienros

Directory.Build.props

@@ -51,7 +51,7 @@
     <BuildArch Condition=" '$([System.Runtime.InteropServices.RuntimeInformation]::OSArchitecture)' == 'X86' ">386</BuildArch>
     <BuildArch Condition=" '$([System.Runtime.InteropServices.RuntimeInformation]::OSArchitecture)' == 'Arm64' ">arm64</BuildArch>
     <BuildArch Condition=" '$(BuildArch)' == '' ">amd64</BuildArch>
-    <DcpDir>$(NuGetPackageRoot)microsoft.developercontrolplane.$(BuildOs)-$(BuildArch)/$(MicrosoftDeveloperControlPlanedarwinamd64Version)/tools/</DcpDir>
+    <DcpDir>$([MSBuild]::EnsureTrailingSlash('$(NuGetPackageRoot)'))microsoft.developercontrolplane.$(BuildOs)-$(BuildArch)/$(MicrosoftDeveloperControlPlanedarwinamd64Version)/tools/</DcpDir>
 
     <!-- TODO: Need to figure out we can automatically detect target framework here. This property
                is specified to support dashboard path metadata generation on the inner loop. -->

src/Aspire.Cli/Projects/DotNetBasedAppHostServerProject.cs

@@ -166,7 +166,7 @@ private XDocument CreateProjectFile(IEnumerable<(string Name, string Version)> p
                     <SkipAddAspireDefaultReferences>true</SkipAddAspireDefaultReferences>
                     <AspireHostingSDKVersion>42.42.42</AspireHostingSDKVersion>
                     <!-- DCP and Dashboard paths for local development -->
-                    <DcpDir>$(NuGetPackageRoot){dcpPackageName}/{dcpVersion}/tools/</DcpDir>
+                    <DcpDir>$([MSBuild]::EnsureTrailingSlash('$(NuGetPackageRoot)')){dcpPackageName}/{dcpVersion}/tools/</DcpDir>
                     <AspireDashboardDir>{_repoRoot}artifacts/bin/Aspire.Dashboard/Debug/net8.0/</AspireDashboardDir>
                 </PropertyGroup>
                 <ItemGroup>