Use pyarrow Tensor dtype
Hi ! We're using the Arrow format for the datasets, and PyArrow tensors are not part of the Arrow format AFAIK:

> There is no direct support in the arrow columnar format to store Tensors as column values.

source: https://github.com/apache/arrow/issues/4802#issuecomment-508494694 @wesm @rok its been around three years. any updates, regarding dataset arrow tensor support? 🙏 I know you must be very busy, would appreciate to learn what is the state of art. I saw the PR is still open [#8510](https://github.com/apache/arrow/pull/8510) Hey @franz101 & @lhoestq!
There is a plan and a PR to create an [ExtensionArray of Tensors](https://github.com/apache/arrow/pull/8510) of equal sizes as well as a plan to do the same for Tensors of different sizes [ARROW-8714](https://issues.apache.org/jira/browse/ARROW-8714). The work stalled a little because it was not clear where TensorArray would live. However Arrow community recently agreed to make a [well-known-extension-type document](https://lists.apache.org/thread/sxd5fhc42hb6svs79t3fd79gkqj83pfh) and I would like https://github.com/apache/arrow/pull/8510 to land there and add an implementation to C++/Python + another language. Is that something you would find beneficial to you? that is a great update, thank you.
it looks like this feature would benefit datasets implementation of [ArrayExtensionArray](https://github.com/huggingface/datasets/blob/9f2ff14673cac1f1ad56d80221a793f5938b68c7/src/datasets/features/features.py#L585-L641). Is that correct @eladsegal @lhoestq?

 TensorArray sounds great ! Looking forward to it :)

We've had our own ExtensionArray for fixed shape tensors for a while now, hoping to see something more standardized by the arrow community.

Also super interested in the extension array for tensors of different sizes cc @mariosasko 
### Feature request

I was going the discussion of converting tensors to lists.
Is there a way to leverage pyarrow's Tensors for nested arrays / embeddings?

For example:
```python
import pyarrow as pa
import numpy as np
x = np.array([[2, 2, 4], [4, 5, 100]], np.int32)
pa.Tensor.from_numpy(x, dim_names=["dim1","dim2"])
```

[Apache docs](https://arrow.apache.org/docs/python/generated/pyarrow.Tensor.html)

Maybe this belongs into the pyarrow features / repo.

### Motivation

Working with big data, we need to make sure to use the best data structures and IO out there

### Your contribution

Can try to a PR if code changes necessary