Emphasize app and package subdirectories in monorepos

For monorepos, something like this would be ideal:

📦 apps
⭐ web
⭐ admin
⭐ mobile

📦 packages
ui
api

or configurable rules such as:

```
"explorer.folderDecorations": {
"apps/*": {
"fontWeight": "bold",
"color": "#FFD700"
}
}
```

or configurable in `.code-workspace`

```
"folders": [
{
"path": "",
"icon": ""
},
],
```

Unfortunately, VS Code doesn't currently support this.