Mention unification in RAR found-conflicts message

Consider a message like

```
warning MSB3277: Found conflicts between different versions of "System.Runtime.InteropServices.RuntimeInformation" that could not be resolved.
    There was a conflict between "System.Runtime.InteropServices.RuntimeInformation, Version=4.0.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" and "System.Runtime.InteropServices.RuntimeInformation, Version=4.0.2.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a".
    "System.Runtime.InteropServices.RuntimeInformation, Version=4.0.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" was chosen because it was primary and "System.Runtime.InteropServices.RuntimeInformation, Version=4.0.2.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" was not.
    References which depend on "System.Runtime.InteropServices.RuntimeInformation, Version=4.0.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" [C:\VisualStudio\VS17PrevPublic\Common7\IDE\PublicAssemblies\System.Runtime.InteropServices.RuntimeInformation.dll].
        C:\VisualStudio\VS17PrevPublic\Common7\IDE\PublicAssemblies\System.Runtime.InteropServices.RuntimeInformation.dll
            Project file item includes which caused reference "C:\VisualStudio\VS17PrevPublic\Common7\IDE\PublicAssemblies\System.Runtime.InteropServices.RuntimeInformation.dll".
                System.Runtime.InteropServices.RuntimeInformation
    References which depend on "System.Runtime.InteropServices.RuntimeInformation, Version=4.0.2.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" [].
        C:\Users\user\.nuget\packages\azure.core\1.25.0\lib\net461\Azure.Core.dll
            Project file item includes which caused reference "C:\Users\user\.nuget\packages\azure.core\1.25.0\lib\net461\Azure.Core.dll".
                C:\Users\user\.nuget\packages\azure.core\1.25.0\lib\net461\Azure.Core.dll
                C:\Users\user\.nuget\packages\azure.identity\1.8.0\lib\netstandard2.0\Azure.Identity.dll
                C:\Users\user\.nuget\packages\azure.security.keyvault.secrets\4.4.0\lib\netstandard2.0\Azure.Security.KeyVault.Secrets.dll
                C:\Users\user\.nuget\packages\nuget.services.keyvault\2.111.0\lib\net472\NuGet.Services.KeyVault.dll
                C:\Users\user\.nuget\packages\nuget.services.configuration\2.111.0\lib\net472\NuGet.Services.Configuration.dll
```

What the message _means_ is that the first reference is the winner, and
what was chosen there will require unification for all the other
assemblies listed in the second part of the message. But what it says is
that the list of assemblies in the second part of the message depend on
the second version, which is not necessarily true--in fact, that's the
list of  references that _can be unified_ to that version.

This isn't a full fix for dotnet#4757 but hopefully makes the message a bit
less misleading.

src/Tasks/AssemblyDependency/ResolveAssemblyReference.cs

@@ -1123,7 +1123,7 @@ quiet at the engine level.
                             LogReferenceDependenciesAndSourceItemsToStringBuilder(conflictCandidate.ConflictVictorName.FullName, victor, logDependencies);
 
                             // Log the reference which lost the conflict and the dependencies and source items which caused it.
-                            LogReferenceDependenciesAndSourceItemsToStringBuilder(fusionName, conflictCandidate, logDependencies.AppendLine());
+                            LogReferenceDependenciesAndSourceItemsToStringBuilder(fusionName, conflictCandidate, logDependencies.AppendLine(), referenceIsUnified: true);
 
                             string output = StringBuilderCache.GetStringAndRelease(logConflict);
                             string details = string.Empty;
@@ -1320,11 +1320,14 @@ internal static string ByteArrayToString(byte[] a)
         /// <summary>
         /// Log the source items and dependencies which lead to a given item.
         /// </summary>
-        private void LogReferenceDependenciesAndSourceItemsToStringBuilder(string fusionName, Reference conflictCandidate, StringBuilder log)
+        private void LogReferenceDependenciesAndSourceItemsToStringBuilder(string fusionName, Reference conflictCandidate, StringBuilder log, bool referenceIsUnified = false)
         {
             ErrorUtilities.VerifyThrowInternalNull(conflictCandidate, nameof(conflictCandidate));
             log.Append(Strings.FourSpaces);
-            log.Append(ResourceUtilities.FormatResourceStringIgnoreCodeAndKeyword("ResolveAssemblyReference.ReferenceDependsOn", fusionName, conflictCandidate.FullPath));
+
+            string resource = referenceIsUnified ? "ResolveAssemblyReference.UnifiedReferenceDependsOn" : "ResolveAssemblyReference.ReferenceDependsOn";
+
+            log.Append(ResourceUtilities.FormatResourceStringIgnoreCodeAndKeyword(resource, fusionName, conflictCandidate.FullPath));
 
             if (conflictCandidate.IsPrimary)
             {

src/Tasks/Resources/Strings.resx

@@ -1692,6 +1692,10 @@
     <value>References which depend on "{0}" [{1}].</value>
     <comment> This will look like references which depend on "A, Version=2.0.0.0 PublicKey=4a4fded9gisujf" [a.dll].</comment>
   </data>
+  <data name="ResolveAssemblyReference.UnifiedReferenceDependsOn">
+    <value>References which depend on or have been unified to "{0}" [{1}].</value>
+    <comment> This will look like references which depend on or have been unified to "A, Version=2.0.0.0 PublicKey=4a4fded9gisujf" [a.dll].</comment>
+  </data>
   <data name="ResolveAssemblyReference.UnResolvedPrimaryItemSpec">
     <value>Unresolved primary reference with an item include of "{0}".</value>
     <comment> This messages is for a reference which could not be resolved, however we have its item spec and will display that. {0} will be somethign like  System or A, Version=xxx</comment>