cleanup(vite): import TempFs from @nx/devkit/internal-testing-utils

Route TempFs through the @nx/devkit/internal-testing-utils subpath export,
matching the other plugin specs. The bare nx/src import tripped the devkit
import-boundary lint rule.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DZ9XvLzj8NvxcB99YZi5da

Author: leosvelperez

packages/vite/plugins/nx-tsconfig-paths.plugin.spec.ts

@@ -1,4 +1,4 @@
-import { TempFs } from 'nx/src/internal-testing-utils/temp-fs';
+import { TempFs } from '@nx/devkit/internal-testing-utils';
 import { join } from 'node:path';
 
 // `var` rather than `let`: transitive imports read `workspaceRoot` while the