SwipeListItem: make space for the actions when !supportsMouseEvents

Summary:
They will be shown all the time and we don't want the content over it

CCBUG: 404755

Reviewers: #kirigami, mart

Reviewed By: #kirigami, mart

Subscribers: plasma-devel

Tags: #kirigami

Differential Revision: https://phabricator.kde.org/D19399