Project Folder Behavior

As a preface, I'm currently using Windows 10.

Modifying the location of a folder after adding it to a Project can lead to strange behaviors. In my test case, I created a new subdirectory within my project folder, and moved a previously established folder to that location.

Despite the change in location, the GUI for Tiled Projects will keep a file in the same position on side panel, and it will not longer be accessible by the project even if the icon remains. In addition, the new location the relocated-folder is not visible unless you add a new map/tileset.

**Summary:**

- Create a project
- Add a folder to that project
- Move the folder to a new directory (preferably a subdirectory)
- Click refresh

I've attached images below.

Reproduce the issue on Windows 10 using the listed project-folder and refresh steps, then trace the project tree refresh behavior in the desktop application. Verify the moved folder remains accessible at its new location and appears without adding a new map or tileset.

Written by the indexing model from the issue text.