fix: wrap the fsspec fs in an AsyncWrapper also if it is called with asynchronouos=False

[nils3er]

If a zarr is open from an fsspec URL, like simplecache::https://some.url.org it failed because the underlying fsspec filesystem (simplecache) is an AsyncFileSystem but it is not instantiated with asynchronouos=True. This led to errors.

This PR wraps the fs in an AsyncFileSystemWrapper to ensure that it is asynchronouos.

TODO:

• [ ] Add unit tests and/or doctests in docstrings
• [ ] Add docstrings and API docs for any new/modified user-facing classes and functions
• [ ] New/modified features documented in docs/user-guide/*.rst
• Changes documented as a new file in changes/
• GitHub Actions have all passed
• Test coverage is 100% (Codecov passes)