/kind feature

This PR add cpp sampler support for mindspore.dataset.GeneratorDataset.

The following new API is being used by mindspore.dataset.GeneratorDataset:

    def __init__(self, source, column_names, column_types=None, schema=None, num_samples=None, num_parallel_workers=1,
                 shuffle=None, sampler=None, num_shards=None, shard_id=None):