Minor refactor to expandPatterns

[fisker]

Description

I found that fast-glob can't glob any file with **/{*.js} (single extension), the original code works because we always have many extensions and filenames in languages.
I guess better pass an array to fast-glob instead to be safer.

Checklist

• I’ve added tests to confirm my change works.
• (If changing the API or CLI) I’ve documented the changes I’ve made (in the docs/ directory).
• (If the change is user-facing) I’ve added my changes to changelog_unreleased/*/XXXX.md file following changelog_unreleased/TEMPLATE.md.
• I’ve read the contributing guidelines.

✨Try the playground for this PR✨

[fisker]

... This happened fixes #15001 somehow. That's something I didn't expected.

[fisker]

I also tested that using array doesn't effect speed.

Test script

import fg from 'fast-glob'

for (const patterns of [
  'node_modules/**/{*.js,*.json,*.md}',
  ['node_modules/**/*.js','node_modules/**/*.json','node_modules/**/*.md'],
]) {
  fg.sync(patterns) // warm up

  const label = JSON.stringify(patterns)
  console.time(label);
  const result = fg.sync(patterns, {dot: true})
  console.log(`${result.length} files found`)
  console.timeEnd(label)
}

>node test.js
15327 files found
"node_modules/**/{*.js,*.json,*.md}": 214.471ms
15327 files found
["node_modules/**/*.js","node_modules/**/*.json","node_modules/**/*.md"]: 194.193ms