Refactor SEFFInterpretationContext

[stiesssh]

The SEFFInterpretationContext has some inconsistencies and questionable design decisions, e.g.:

• Children have the same calledFrom attribute as their parents. However, i think a SEFFIC that has a parent (i.e. was not called) should not have a caller. If at any point, a child must know whether it was called, or by whom it was called, the query should be passed to the parent.
• Children have the same calledFrom attribute as their parents, but not their callOverWireRequest attribute. However i think, those two attributes should always appear together, i.e. either both are set or both are unset.
• Regarding the CallOverWireRequest, most information in there are redundant, and when progressing with the SEFF interpretation, we rely mostly on the GeneralEntryRequest anyway. Can we get rid of the CallOverWireRequest or at least slim it down?

Goal of this issue is to discusse the point above and fix them if reasonable.