fsspec proxy and client

Allows reading/writing files via standard fsspec/python operations via a proxy, which doesn't expose any of its internal credentials.

This is particularly useful for pyscript, which cannot call the backend packages required to talk to remote filesystems, like botocore.

Demo

This is for running the example locally. Further docs will be written when we have agreed on a final layout of this repo and code.

With a prepared environment including s3fs.

$ git clone https://github.com/fsspec/fsspec-proxy
$ cd fsspec-proxy
$ pip install ./fsspec-proxy
$ fsspec-proxy
$ # new console, same directory
$ cd example
$ uvx pyscript run . --port 8899