[wayland] Send VirtualDesktop::done after editing a property

Summary:
The protocol is double buffered, after changing the name done should be
sent so that clients update.

Test Plan:
Changed a VD name on wayland
Pager tooltip updated

Reviewers: KWin, zzag

Reviewed By: KWin, zzag

Subscribers: zzag, kwin

Tags: KWin

Differential Revision: https://phabricator.kde.org/D18513