clients/simple-egl: Implement fractional-scale protocol support
Fractional scale is increasingly common in the Wayland ecosystem. Thus, given simple-egl's role as egl example client, implement support for the new protocol - even though Weston itself does not support it yet.
Together with buffer_scale and buffer_transform this ensures simple-egl provides optimally sized and oriented buffers.
Mainly tested with https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2394
Edited by Robert Mader