Revert "Port to PlasmaExtras version of Highlight"
It requires Plasma Framework 5.93 which is higher than the dependency allowed by 22.04 release.
This reverts commit 68331057.
Dependency freeze for 22.04 was 10 March at which point Plasma framework 5.93 (nor 5.92) was not released yet.
Edited by Kai Uwe Broulik