Vite: Use posix paths for glob

[IanVS]

Closes storybookjs/builder-vite#554

What I did

New vite projects are failing in Windows because of a change in an updated glob package which enforces forward-slashes for glob paths.

So, we'll use path.posix to join paths in the vite builder for globs.

How to test

I don't have access to a windows box, so I'm not able to test. And we don't test Windows in CI. I'm hoping that maybe @joshwooding or someone else can help test this out.

Checklist

• Make sure your changes are tested (stories and/or unit, integration, or end-to-end tests)
• Make sure to add/update documentation regarding your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Maintainers

• If this PR should be tested against many or all sandboxes,
  make sure to add the ci:merged or ci:daily GH label to it.
• Make sure this PR contains one of the labels below.

["cleanup", "BREAKING CHANGE", "feature request", "bug", "documentation", "maintenance", "dependencies", "other"]

[shilman]

import { join } from 'node:path/posix';? not sure if it makes a difference in node

[IanVS]

Do you prefer the destructured version? I slightly prefer the namespaced version, just because it's clear when it's being used where it's coming from. posixPath.join() vs just join(). But I don't feel strongly about it and happy to change if you'd like.

[shilman]

Don't feel strongly. I think @ndelangen was making a push towards the namespaced version (but maybe only in browser code, for tree shaking?), so maybe he can comment here.