Add node reference system to process node result as well

[NicolasMahe]

We should also implement it on the node of type result as they are also linked to an execution so the outputs can be read at anytime.

[krhubert]

Hasn't it already done by @antho1404, has it?

[antho1404]

Now we can reference a trigger with the direct child only, we should be able to reference a result trigger from any node. It shouldn't be complicated tho, just a check on the type if it's a task or a result.

[NicolasMahe]

attempt done in https://github.com/mesg-foundation/engine/pull/1740