Don't map screenedge approach window if edge is only used for touch

Summary:
Another regression from enabling touch support on X11.
The approach window for pointer input gets unmapped as soon as the mouse
enters the window. This ensures that mouse motion events are not stolen
from other applications. But with the touch events we did not even react
on the enter event if it's not activated for pointer. The result was an
area around the screenedge being blocked for pointer input.

This change only creates and maps the approach window if the edge is
activated for pointer input.

BUG: 378951

Test Plan:
Activated edges through pointer and touch, reconfigured and tested
motion events

Reviewers: #kwin, #plasma

Subscribers: plasma-devel, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D5528