Add 'hasTrait' support to Operation.

This is accomplished by adding a new callback to AbstractOperation that takes a ClassID for a given trait type and compares that against the ClassIDs for the traits used when registering an operation. This allows for opaquely querying if an operation was registered with a given trait, e.g:

Operation *op = ...;
bool singleResult = op->hasTrait<OpTrait::OneResult>();

PiperOrigin-RevId: 257007710