 Add support for `Sequence(Audio/Image)` feature in `push_to_hub`
### Feature request

Allow for `Sequence` of `Image` (or `Audio`) to be embedded inside the shards.

### Motivation

Currently, thanks to #3685, when `embed_external_files` is set to True (which is the default) in `push_to_hub`, features of type `Image` and `Audio` are embedded inside the arrow/parquet shards, instead of only storing paths to the files.

I've noticed that this behavior does not extend to `Sequence` of `Image`, when working with a [dataset of timelapse images](https://huggingface.co/datasets/1aurent/Human-Embryo-Timelapse).

### Your contribution

I'll submit a PR if I find a way to add this feature