[FEATURE] Handle errorneous flag evaluation without exceptions

[aepfli]

So far, we used exceptions to handle our flow control, but Exceptions are costly. In the end, we enriched our
evaluation Details with errorCode and errorMessage. If desired, the providers can also handle this to reduce the execution footprint in erroneous cases, which don't have to be exceptions. Till now, we also converted those into exceptions and threw them, with a little code change, we would return already the details, and call the hooks, without exceptions being thrown.

For example, FlagNotFound is such a case; it can be expected and not exceptional. Hence, the exception flow might add too much overhead to performance-critical environments.

This implementation allows the prover implementors to decide whether to support either or both.

In Java and JavaScript we are doing this already see java pr