tmf: Add a StateSystemDisposedException

tmf: Add a StateSystemDisposedException

Once a state system is diposed, no future queries should be run on
it. If such a thing happens, the new StateSystemDisposedException
will be thrown. This can help views know that they should stop
doing queries.

Change-Id: I1a887cd322a1ac1ee6ffb1705c0c7e794f848f1f
Signed-off-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Reviewed-on: https://git.eclipse.org/r/8497
Reviewed-by: Patrick Tasse <patrick.tasse@gmail.com>
IP-Clean: Patrick Tasse <patrick.tasse@gmail.com>