This PR rewrites many of the general server tests on top of xf86-input-emulated driver (p12tic/xf86-input-emulated!1). It depends on xorg-gtest!2 (closed), xorg/xserver!510 (merged).
Testing based on 1.20.8 release showed that the tests are stable and thus useful.
At this moment many touch ownership tests fail. The failures seem to be genuine functionality breakage. I've bisected the failures to xorg/xserver@98e3db2a. So this work already helped to uncover a regression.