Skip splitting for paths

Author: Forgind

src/Cli/Microsoft.TemplateEngine.Cli/TemplatePackageCoordinator.cs

@@ -208,7 +208,8 @@ internal async Task<NewCommandStatus> EnterInstallFlowAsync(InstallCommandArgs a
 
             foreach (string installArg in args.TemplatePackages)
             {
-                string[] split = installArg.Split(["::"], StringSplitOptions.RemoveEmptyEntries).SelectMany(arg => arg.Split('@', StringSplitOptions.RemoveEmptyEntries)).ToArray();
+                bool isPath = File.Exists(installArg) || Directory.Exists(installArg);
+                string[] split = isPath ? new[] { installArg } : installArg.Split(["::"], StringSplitOptions.RemoveEmptyEntries).SelectMany(arg => arg.Split('@', StringSplitOptions.RemoveEmptyEntries)).ToArray();
                 string identifier = split[0];
                 string? version = split.Length > 1 ? split[1] : null;
                 foreach (string expandedIdentifier in InstallRequestPathResolution.ExpandMaskedPath(identifier, _engineEnvironmentSettings))