Remove io.shiftleft.semanticcpg.language.operatorextension

[bbrehm]

The corresponding classes extend from Noderef.

This means that they create a second Noderef referencing the same underlying Node.

However, overflowdb cannot deal with that: The entire logic (e.g. https://github.com/ShiftLeftSecurity/overflowdb/blob/5bf234034dc7b58edf0983753adb253ce340578a/core/src/main/java/overflowdb/NodeRef.java#L91) synchronizes the storage on the Ref, not the node.

Afaiu this part of the API is not used in prod. So let's get rid of it, and afterwards add checks in overflowdb that guarantee the right invariant (every node can only have a unique reference to it).

cc @fabsx00 because you know best which parts of the API are important for whom, and @mpollmeier because you know overflowdb best.