Close #19695 : Add Basic and Bearer Authorization to the CPP Pistache generator

[mowijo]

This PR implements a solution to #19695 .

The implementation is a bit different than what agreed upon in #19695. Because none of teh ApiImplementations share a common object apart from a Pistache::Router instance, there are no central object to install a shared credentials/token check on. I do not feel that would belong in the Pistache::Router class.

However, a shared authentication mechanism can be obtained by assigning a such in main. For example:

bool tokenValidator(HttpBearerToken &token)
{
    return (token.token == "Zm9vYmFyCg==");
}

int main() { 
  ...
  for (auto api : apiImpls) {
      api->setBearerTokenAuthenticator(&tokenValidator);
      api->init();
  }
  ...
}

and it may be overwritten in the individual implementations like

void PetsApiImpl::init() 
{
 PetsApi::setupRoutes(); 
   this->setBearerTokenAuthenticator([](){
      return (token.token == "Rk9PQkFSCg==");
   }
 );
}

and the same holds true for Basic.

If the expected headers are missing or malformed or the assigned validators returns false, a 401 is returned.

User Data

Both HttpBearerToken and HttpBasicCredentials can carry userdata as void* from the validator to the endpoint implementation. This can be used to propagate data from the validator that is expected to be reused in the endpoint. For example user ids. this can be accomplished like this:

bool tokenValidator(HttpBearerToken &token)
{
    if(token.token == "Zm9vYmFyCg==")
    {
        const int userIdOfFoo = 99;
        token.userdata = std::unique_ptr<void,std::function<void(void*)>>(
            reinterpret_cast<void*>(new int(userIdOfFoo)),
            [&](void* ptr)
            {
                int * value = reinterpret_cast<int*>(ptr);
                delete value;
            }
            );
        return true;
    }
    return false;
}

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Tagging

@ravinikam , @stkrwork , @etherealjoy , @MartinDelille , @muttleyxd