Sometimes on_all_workspaces is requested by the client/user, and sometimes
its calculated implicitly due to internal state. We split this up so that
we know when the user has explicitly asked for sticky window, when e.g.
setting wmspec properties or storing session info.

on_all_workspaces means this window is visible on all workspaces.

on_all_workspaces_requested, means the user explicitly made the window
sticky somehow (via imported session, _NET_WM_STATE from another wm,
toggled in the window menu, etc). It always implies on_all_workspaces is
TRUE.

Right now the only time we set on_all_workspaces is for override-redirect
windows, but later we can add a "windows on non-primary monitor are not
part of the workspace switching" feature.

https://bugzilla.gnome.org/show_bug.cgi?id=609258