Trigger rebuild when the CLI changed

- Stamp each project with the CLI version it was last compiled with
- Rebuild those projects with a local version file that does not match the one of the current CLI that is building it

src/dotnet/Program.cs

@@ -159,8 +159,7 @@ namespace Microsoft.DotNet.Cli
         
         private static string GetCommitSha()
         {
-            // The CLI ships with a .version file that stores the commit information
-            var versionFile = Path.GetFullPath(Path.Combine(AppContext.BaseDirectory, ".version"));
+            var versionFile = DotnetFiles.VersionFile;
             
             if (File.Exists(versionFile))
             {