Word-wrap long tooltips

Summary:
This patch fixes long tooltips so that they word-wrap instead of overflowing.

BUG: 396385
FIXED-IN: 5.55

Test Plan: {F6552271, size=full}

Reviewers: mart, #plasma, #kirigami, davidedmundson

Reviewed By: #plasma, davidedmundson

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D18306