Suppoer sharing text from kdeconnect-cli

Summary:
Can be used with the share-text argument like
kdeconnect-cli -d adsjsakldsjsa --share-text "hello"

Reviewers: KDE Connect, albertvaka

Reviewed By: KDE Connect, albertvaka

Subscribers: kdeconnect

Tags: KDE Connect

Differential Revision: https://phabricator.kde.org/D17242