Add option to enforce validation based on referenced WoT model about ditto

[thjaeckle]

I think that we need to validate always what the target state of the complete thing (or feature if only a feature was modifier) would be against the model.

So after enforcement (different permissions should not yield different validation results), but before applying a modify command to the persistence.

We should also monitor how much time validation takes, by adding metrics (spans) to the existing signal processing trace.

It would ne nice to have the validation as separate Java Module so that it could also be used as a library.

[thjaeckle]

Another idea on the enforcement:
Configure a list of auth subjects (also supporting wildcards) for which validation is not done.

I am thinking especially about eg connections where we don't necessarily rely on a user input to validate.
Whereas for api users, eg authenticated via JWT and the http api, it would be important to validate all provided data.