temp/plasma-workspace: fork from Alpine to apply Librem 5 specific patch

This fixes the visual artifacts for Plasma Mobile on Purism Librem 5.

To explain bit more,

This variable needs to be set for just compositor and not clients(apps). Librem 5 device package sets it globally using /etc/profile.d/00-mesa.sh. I need some way to unset it, and this is best fitting place.

I also don't have a way of setting it for just one process (kwin_wayland) since clients inherit the environment of the kwin_wayland.