Bug 440056

SUMMARY
When we pass the text with html code, that contains <a href=""> links to some urls, to the kdialog msgbox content - it renders successfully even with underlined blue links, but those links are not clickable.

STEPS TO REPRODUCE
1. Launch the command in console:
```
kdialog --msgbox '<h1>KDE is great!</h1><a href="https://kde.org">All glory to <strong>KDE</strong>!</a>'
```

2. See the window and try to click on link, it does nothing.

3. Try to pass same text in passivepopup mode:
```
kdialog --passivepopup '<h1>KDE is great!</h1><a href="https://kde.org">All glory to <strong>KDE</strong>!</a>'
```
It will be clickable.

OBSERVED RESULT
The links are not clickable in msgbox mode.

EXPECTED RESULT
The links should be clickable in msgbox mode too!

SOFTWARE/OS VERSIONS
Operating System: Kubuntu 21.04
KDE Plasma Version: 5.22.3
KDE Frameworks Version: 5.84.0
Qt Version: 5.15.2
Kernel Version: 5.11.0-22-generic (64-bit)
Graphics Platform: X11
Processors: 4 × Intel® Core™ i3-4330 CPU @ 3.50GHz
Memory: 15.5 GiB of RAM
Graphics Processor: Mesa DRI Intel® HD Graphics 4600