USB creator does not work in non-Gnome session, but crashes

[Michał J. Gajda]

To replicate the bug:

1. `apt-get install -y sway` to install alternative window manager.
2. After starting session use `Mod4 (Win key) + Enter` to open terminal window.
3. Start `usb-creator-gtk` and try to create bootable USB driver.
4. You will see `usb-creator-gtk` display message window `Could not write the disk image (/home/m/Downloads/ubuntu-22.10-beta-desktop-amd64.iso) to the device (/dev/sda).`
5. Then `usb-creator-gtk` crashes without asking for any credentials.

I am not sure, it looks like `usb-creator-gtk` has a hidden dependency on some DBus service, but does not try to invoke it to get access to the flash drive.

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: usb-creator-gtk 0.3.13
ProcVersionSignature: Ubuntu 5.15.0-48.54-lowlatency 5.15.53
Uname: Linux 5.15.0-48-lowlatency x86_64
ApportVersion: 2.20.11-0ubuntu82.1
Architecture: amd64
CasperMD5CheckResult: pass
Date: Tue Oct 4 00:04:54 2022
InstallationDate: Installed on 2022-09-05 (28 days ago)
InstallationMedia: Ubuntu 22.04.1 LTS "Jammy Jellyfish" - Release amd64 (20220809.1)
PackageArchitecture: all
SourcePackage: usb-creator
UpgradeStatus: No upgrade log present (probably fresh install)