fix[closes #4482]: [Bug]: KDE/Wayland Desktop Entry creation failed

[g33z]

Description

Observation

xdg-desktop-portal-kde has a buggy Dynamic Launcher portal implementation. 👯

The QML dialog (DynamicLauncherDialog.qml) is missing required properties (launcherIcon, launcherName), causing the portal to reject requests before the confirmation dialog even displays.

The code

When the portal fails, there is the fallback creating .desktop files manually.

However that fallback only catches errors from dynamic_launcher_install(), not from dynamic_launcher_prepare_install_finish() where KDE's rejection actually occurs.

I caught the error within libportal and added a general fallback functionality adding the .desktop files to ~/.local/share/applications for menu entries as well as ~/Desktop for actual desktop shortcuts.

I did add the necessary permissions in the development build json.
Hope that is how that was intended... 😅

Fixes #4482

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality) - actually adding a Desktop icon, not only a menu entry 😛
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

I created multiple entries and observed the logs inside the terminal.

Provide instructions so we can reproduce.

• have KDE Plasma installed :P
• Try to create a Desktop shortcut for an added application

[g33z]

Only to connect the two, I am mentioning #4012 here.