`app_id` declared by `QWaylandWindow::initWindow()` is empty if the executable starts with a dot

On NixOS, a Linux distribution, a lot of programs are wrapped by shell scripts to inject e.g. additional variables or CLI flags. This means that `foo` is a shell-script and `.foo-wrapped` is the actual program being execed into by the wrapper.

The `app_id` on Wayland (in `QWaylandWindow::initWindow()`) is determined by using `QFileInfo::baseName()` on the application's file path (`QCoreApplication::instance()->applicationFilePath()`).

Since the `applicationFilePath` is usually the one where the filename is `.foo-wrapped`, the base-name is empty and thus the `app_id` is also empty.

A possible workaround for this is to use `QFileInfo::fileName()` instead.