Surface visibility attribute not set to false when minimized

It's also not set to false when occluded, but this is because we don't currently understand opaque regions of Wayland surfaces. Setting it to false when minimized at least should be easy though.

The issue names no files or tests. Start by locating the compositor's Wayland surface visibility handling and trace what happens when a surface is minimized. Done means the surface visibility attribute becomes false when minimized; handling occluded surfaces is explicitly outside this issue.

Written by the indexing model from the issue text.