`_ls` overrides base class in incompatible manner

[kylebarron]

Here you default to detail=False in _ls

https://github.com/fsspec/s3fs/blob/b4d3fa89f1accbfc2186f1d42d07be15bc9df101/s3fs/core.py#L1021

but in the base class of AsyncFileSystem you default to detail=True.

Is it intentional to override the base class in this way? Is every implementor intended to disregard the default value of detail in the base class?