Replace the p2p-loader with IPFS

[tomaka]

The current peer-to-peer loaded uses a custom peer-to-peer network because it's simple to implement.
IPFS, due to its popularity, seems like a better choice for publishing modules. The tooling is already there, and filecoin is now a thing as well.

There exists a rust-ipfs project, but it can't really be compiled to wasi because wasi doesn't support sockets (the compilation should succeed, but it can't work).

Once sockets are supposed, we can think of switching.

[tomaka]

Major difficulty is that rust-ipfs uses tokio.