Fix casing on case-insensitive filesystems

[adrum]

I noticed an issue where vscode seems to be passing a cached filename on case-insensitive file systems on file events. This PR pulls the latest filename from the system by grabbing the current casing before passing off the file path in PintEditService.formatFile function.

Steps to reproduce:

0. Enable autoformatting on file save in .vscode/settings.json

{
  "editor.formatOnSave": true,
  "editor.codeActionsOnSave": {
    "source.fixAll.eslint": "explicit"
  },
  "laravel-pint.enable": true,
  "laravel-pint.configPath": "pint.json",
  "laravel-pint.executablePath": "vendor/bin/pint",
  "[php]": {
    "editor.defaultFormatter": "open-southeners.laravel-pint"
  }
}

1. Setup a pint.json config file like so:

{
  "preset": "laravel",
  "rules": {
    "psr_autoloading": true
  }
}

2. In VSCode, Create test file at app/Actions/wrongCasing.php and save it with autoformatting:

namespace App\Actions;

class wrongCasing {}

3. Rename the file to the proper casing in vscode app/Actions/wrongCasing.php > app/Actions/wrongCasing2.php > app/Actions/WrongCasing.php
4. Save the file to trigger formatting.

The file itself still has a class name of wrongCasing instead of WrongCasing derived from the filename.