Add a filter+cache mechanism for addon needing to be called

in relation with #111,
The computation of the order may take some time and decrease execution time since it is currently done before and after each step.

We should provide a way to cache this for a given execution.

Additionally, we can add in the addon definition some information about the list of notification/event that the addon is really interested in.

By default, an addon would notified about everything, but if we can filter on which events an addon must be notified, then we would also save some time by not calling the "empty" method for it.

see how the addons are called in https://github.com/eclipse/gemoc-studio-modeldebugging/blob/master/framework/execution_framework/plugins/org.eclipse.gemoc.executionframework.engine/src/org/eclipse/gemoc/executionframework/engine/core/AbstractExecutionEngine.java