Summary:
Create output devices in virtual backend. For that the setVirtualOutputs call
can only come after the Wayland server has been initiliazied such that the
display exists to create the output and output device interfaces. Tests have
been adjusted for that.
Test Plan:
```
98% tests passed, 3 tests failed out of 148
Total Test time (real) = 362.97 sec
The following tests FAILED:
33 - kwin-testInternalWindow (Failed)
39 - kwin-testPointerInput (Failed)
101 - kwin-testMoveResize (Failed)
```
Failing of these tests looks unrelated to the change.
Reviewers: #kwin
Subscribers: kwin
Tags: #kwin
Maniphest Tasks: T11459
Differential Revision: https://phabricator.kde.org/D23477
cd6b69a4d2