Only replace first basePath occurrence in dump source href

[fritz-c]

With a custom value for config('app.editor.base_path'), you can essentially map a local path (inside a docker container in my case) to a path that exists on the dev's machine so they can open it in their editor. However, with the existing code, if my base path in the container is, say, /app, and the path I'm trying to get the source href to has that path duplicated, like with /app/app/Models/User.php, I'll end up with both instances of the base path mapped over to the custom base path (e.g., /my-project/my-project/Models/User.php if config('app.editor.base_path') is /my-project).
This PR just makes the path replacement more limited to avoid that issue.