Don't store logical monitor specific state in an array where the index
from the monitor manager is used as index locally. Instead just use
table associating a logical monitor with a monitor specific state
holder, and store the state in there. This way we don't have the
workspace implementation relying on implementation details of other
units.
https://bugzilla.gnome.org/show_bug.cgi?id=777732
68f3b5849a