distrobox-export doesn't handle .desktop filenames with whitespace

[abyszuk]

Describe the bug
If the .desktop filename contains whitespace, distrobox-export command seems to get confused.
It will print a few error messages coming from grep and then it seems to just hang. At least I've given up waiting after 15 minutes.

To Reproduce
I have following files in one of the directories:

adrian@vivado2018:~/praca$ ls -h ~/.local/share/applications/
Add Design Tools or Devices 2021.2_1644315538793.desktop 
Uninstall 2021.2_1644315538779.desktop  
Vitis HLS 2021.2 Command Prompt_1644315538645.desktop 
Vivado 2021.2_1644315538630.desktop 
Xilinx Vitis 2021.2_1644315538618.desktop
Documentation Navigator_1644315538843.desktop 
Uninstall DocNav_1644315538855.desktop 
Vitis HLS 2021.2_1644315538752.desktop 
Xilinx Information Center_1644315538977.desktop 
vivado2018.1.desktop
Manage Xilinx Licenses 2021.2_1644315538770.desktop 
Uninstall Xilinx Information Center_1644315538922.desktop 
Vivado 2021.2 Tcl Shell_1644315538624.desktop 
Xilinx Software Command Line Tool 2021.2_1644315538097.desktop

Expected behavior
Filenames containing whitespace are handled correctly.

Logs

adrian@vivado2018:~/praca$ distrobox-export --app vivado          
grep: /home/adrian/.local/share/applications/Vivado: No such file or directory
grep: 2021.2: No such file or directory
grep: Tcl: No such file or directory
grep: Shell_1644315538624.desktop: No such file or directory
grep: /home/adrian/.local/share/applications/Vivado: No such file or directory
grep: 2021.2_1644315538630.desktop: No such file or directory
^C

Desktop (please complete the following information):
Ubuntu 22.04 with Docker installed from PPA.
Distrobox installed from git repo (cloned 07.04.2023)

Additional context
Possibly related to #694 as I've noticed both these issues at once.