wayland: Schedule a configure event when borders change
Window::checkWorkspacePosition() before the window is mapped is still problematic and should be avoided as it can produce undesired constrained client size (1x1).
Given that XdgToplevelWindow tries to maintain the same frame geometry size, it should be enough to schedule another configure event instead. It is going to be in line with the other decoration logic in the XdgToplevelWindow and it's a better way to handle async geometry updates.