feat: support glob patterns in editor.fileTree.allowEdits

[AriPerkkio]

• Continues feat: add files via file tree #314

Adds support for users to specify one or multiple glob patterns in editor.fileTree.allowEdits.

---
type: lesson
title: Example
editor:
  fileTree:
    allowEdits:
      # Items in root
      - "/*"

      # Only "allowed-filename-only.js" inside "/first-level" folder
      - "/first-level/allowed-filename-only.js"

      # Anything inside "second-level" folders anywhere
      - "**/second-level/**"
---

When students attempt to create file that doesn't match these patterns, we show an error dialog:

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[Nemikolh]

Really good work on this! 🤩

Some very minor things, and let's ship this! 💪

[Nemikolh]

Yay! 🤩🤩