qmlls formatting is slow

We got feedback that `qmlls` formatting is slow in this bug report https://bugreports.qt.io/browse/VSCODEEXT-85

I tested with both the `qmlformat` executable and the formatting in the vscode extension with `qmlls`

The `qmlformat` results are like below
```

> time /Users/orkun/Qt/6.7.2/macos/bin/qmlformat Main.qml --i

________________________________________________________
Executed in   65.20 millis    fish           external
   usr time   43.54 millis    0.21 millis   43.34 millis
   sys time   14.27 millis    1.54 millis   12.73 millis

```

I formatted the same file and recorded my screen because I couldn't find any tool to measure it. It seems like it takes between 1-2 seconds.

What could be the root cause of this? Do you think there is a way to improve it?

The test file is `Main.qml` in the calculator example. I copied some properties to make it big.

Main.qml