Removed Connection::project()

[morozov]

Q	A
Type	improvement
BC Break	yes

As originally discussed in #3703 (comment), the method has more limitations and caveats than provides real use:

1. It fetches all data in memory which is often inefficient (see Add iterators for non pdo drivers. #2718).
2. It fetches rows in memory one by one instead of using fetchAll().
3. It doesn't allow to specify the statement fetch mode since it's instantiated internally.
4. It can be easily replaced with:

   foreach ($conn->executeQuery($query, $params, $types) as $value) {
      yield $function($value);
   }