Add PHP file type icon from
[file-icons/icons](https://github.com/file-icons/icons)


[https://github.com/file-icons/icons/blob/master/svg/PHP.svg](https://github.com/file-icons/icons/blob/master/svg/PHP.svg)

<img width="408" alt="Screenshot 2024-01-31 at 23 14 55"
src="https://github.com/zed-industries/zed/assets/44226349/26c3d19d-3a5d-4fc6-b551-f5351ba62b7d">


Release Notes:

- Added PHP file type icon.