xwayland: Include xwayland-window.h from xwayland-glamor-eglstream.c
The main purpose of this MR is the last commit, fixing #954 (closed) .
The previous commit enables the Xwayland eglstream code in the CI pipeline, which would have caught the problem. Since it requires building a new docker image, also do various changes getting us closer to the CI state of art in Mesa, and making the image smaller.