Just as the gtk3 plugin isn't named GNOME, rename kde5 to kf5, as
it is based on the KDE frameworks 5 libraries.
This also includes:
* a convenience alias to load the kf5 VCL plugin in case someone
requests the kde5 plugin.
* keep convenience kde5 configure switch, but warn about it
* rename detected desktop from kde5 to plasma5
Change-Id: I6764a05b81a5edbf284484c234fee2649aacf735
Reviewed-on: https://gerrit.libreoffice.org/75313
Tested-by: Jenkins
Reviewed-by: Jan-Marek Glogowski <glogow@fbihome.de>
d3c6ac6d0f