[MNT] Reduce Task Constructor Duplication

I agree with this comment on code duplication: https://github.com/openml/openml-python/blob/main/openml/tasks/task.py#L2
All 6 task classes have nearly identical `__init__` methods with 8-10 parameters each. This creates duplicated code.

The differences between the task-like classes can be handled by class attributes.