fix: treat all optimizeDeps.entries values as globs

[jamesopstad]

Description

This fixes an issue introduced in #15853 that meant globs containing \\ could be treated as literals rather than globs. This would then lead the filesystem check here -

vite/packages/vite/src/node/optimizer/scan.ts

Line 281 in 8679a43

fs.existsSync(entry),

- to fail because the path would include \. It also improves upon the previous approach because entries explicitly including node_modules can now be used alongside other glob entries.

These changes mean that explicitly passing entries containing the environment's build output directory no longer work. It's not clear why this feature was introduced but if it would be considered breaking to remove it then I can add in the extra handling.

[Jinjiang]

For more information, I've created a reproduction of #15853 originally trying to solve:
https://github.com/Jinjiang/reproductions/tree/vite-entries-in-node_modules-20250516

From what I've tested it works as expected.

Thanks.