tmf: Add proper public methods to internal.tmf.core.statesystem

tmf: Add proper public methods to internal.tmf.core.statesystem

Those are already in internal packages, so they will not be API methods,
but by making them public, it makes it possible to access them directly for
unit testing.

Change-Id: I320317302ed6d6ccfc414d3666d2b657c1cd3207
Signed-off-by: Alexandre Montplaisir <alexmonthy@voxpopuli.im>
Reviewed-on: https://git.eclipse.org/r/19884
Tested-by: Hudson CI
Reviewed-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
IP-Clean: Matthew Khouzam <matthew.khouzam@ericsson.com>