In theory we support Qt 5.6 (because of SailfishOS) but in practice we are not checking that in the CI so probably we broke the compatibility long ago. Also, I don't think anyone is using this code in SailfishOS, so we can greatly simplify the code by requiring Qt 5.15 or later.
Uses KPluginLoader+KPluginMetadata instead.
Describes plugins in json instead of desktop files. These desktop files are
then embedded into the .so file. All the plugins will be in a kdeconnect/
directory, and those will be the ones to look for.
Note it doesn't drop the KService dependency as KIOCore is a KDE Connect
dependency as well.
REVIEW: 123042