Fix crash during upgrade when content globs escape root of project

[RobinMalfait]

This PR fixes an issue where globs in you content configuration escape the current "root" of the project.

This can happen if you have a folder, and you need to look up in the tree (e.g.: when looking at another package in a monorepo, or in case of a Laravel project where you want to look at mail templates).

This applies a similar strategy we already implement on the Rust side.

1. Expand braces in the globs
2. Move static parts of the pattern to the base of the glob entry object

---

Given a project setup like this:

.
├── admin
│   ├── my-tailwind.config.ts
│   └── src
│       ├── abc.jpg
│       ├── index.html
│       ├── index.js
│       └── styles
│           └── input.css
├── dashboard
│   ├── src
│   │   ├── index.html
│   │   ├── index.js
│   │   ├── input.css
│   │   └── pickaday.css
│   └── tailwind.config.ts
├── package-lock.json
├── package.json
├── postcss.config.js
└── unrelated
    └── index.html

7 directories, 14 files

If you then have this config:

// admin/my-tailwind.config.ts
export default {
  content: {
    relative: true,
    files: ['./src/**/*.html', '../dashboard/src/**/*.html'],
                            //  ^^  this is the important part, which escapes
                            //      the current root of the project.
  },
  theme: {
    extend: {
      colors: {
        primary: 'red',
      },
    },
  },
}

Then before this change, running the command looks like this:

After this change, running the command looks like this: